Report on the Radiolaria/Sphaeroidea

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Report on the Radiolaria
by Ernst Haeckel

Sphaeroidea

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1579094Report on the Radiolaria — SphaeroideaErnst Haeckel

Order II. SPHÆRELLARIA, Haeckel, 1881.

Sphærellaria, Haeckel, 1881, Prodromus, p. 421.
Sphæridea vel Peripylea, Hertwig, 1879, Organismus der Radiol., p. 133.

Definition.—Spumellaria with latticed or spongy shell.

The order Sphærellaria, the second order of Radiolaria, comprises all those Spumellaria in which the skeleton is a latticed or fenestrated, often more or less spongy, siliceous shell. Originally this shell is a simple extracapsular lattice-sphere, in which the central capsule is included; from this simple ancestral form an enormous mass of different and often very complicated forms is derived; this order is by far the largest, and in morphological respects the most important and most interesting, of all Radiolaria. It contains not less than twenty-eight different families, three hundred and five genera, and more than sixteen hundred species.

In my Monograph (1862) seven families appertaining to this group are described—the Ethmosphærida, Cladococcida, Ommatida, Spongurida, Discida, Lithelida, and Collosphærida. The astonishing increase of this group by the detection of a large series of new and interesting forms, and particularly of important connecting forms between very different branches of it, now enables me to give a much better arrangement. I discern now four suborders or sections of Sphærellaria, according to the different geometrical form of the central capsule and of the latticed shell enveloping it. The first of these, and the common ancestral group of the whole order, is the Sphæroidea, with spherical capsule; in the Prunoidea it becomes ellipsoidal or cylindrical by prolongation of one axis; in the Discoidea lenticular or discoidal by shortening of one axis; in the Larcoidea lentelliptical, or triaxon-ellipsoid, by different growth of the capsule in three different "dimensive axes."

Synopsis of the Four Suborders of Sphærellaria.

Central capsule spherical.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Shell a simple sphere or a system of concentric spheres,	1. Sphæroidea.
Central capsule ellipsoidal or cylindrical.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Shell a simple ellipsoid or a cylinder with annular transverse constrictions,	2. Prunoidea.
Central capsule lenticular or discoidal.		Shell a biconvex lens or a flat disk,	3. Discoidea.
Central capsule lentelliptical or triaxon.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Shell a triaxon-ellipsoid, with three different axes,	4. Larcoidea.

Suborder I. SPHÆROIDEA, Haeckel.

Sphæroida, Sphæridea, Sphærida, Haeckel, 1878, Protistenreich, p. 103.
Sphæridea, R. Hertwig, 1879, Organismus der Radiol., p. 39.

Definition.—Spumellaria with spherical central capsule (very rarely somewhat modified, or allomorphous); with spherical fenestrated siliceous shell (often an endospherical polyhedron, very rarely of more modified, subspherical form or allomorphous). Growth of the shell in the three dimensive axes equal.

The suborder Sphæroidea, the first and most important of the four of the Sphærellaria, comprises those Spumellaria in which the original geometrical spherical form is quite constantly preserved in the central capsule, and commonly also in the fenestrated shell enveloping the latter, although in many forms the sphere is more or less modified; very frequently it is an "endospherical polyhedron," i.e., a polyhedron all the angles (or the nodes of the network) of which lie upon the surface of a geometrical sphere; more rarely the spherical form is more or less modified and irregular. In the great majority of Sphæroidea there is no external indication of the three dimensive axes; but in many forms they are indicated by the regular position of certain external radial spines or internal radial beams. However, in no case are those three axes expressed in the form of the shell itself and of the enclosed spherical central capsule; this is the main character by which the Sphæroidea differ from the following sections:—Prunoidea, Discoidea, Larcoidea, all three of which arise from them.

The section Sphæroidea, in the sense here restricted, was founded by me in my Protistenreich (1878, p. 103) and adopted by Hertwig (1879) in his Organismus der Radiolarien (p. 39). The different groups appertaining to this large section were characterised more accurately in my Prodromus (1881, pp. 448-456); there I gave the characters of six subfamilies with thirty tribes, containing ninety-three genera. Formerly, in my Monograph (1862), the Sphæroidea were disposed in five different families:—Ethmosphærida, Cladococcida, Ommatida, Spongosphærida, Collosphærida. At that time I could not separate them sufficiently from some Acantharia and Phæodaria, which have a similar spherical lattice-shell.

As the number of different genera and species in the Sphæroidea is much greater than in all other sections of Spumellaria, many forms were already described by former authors. In the oldest system of Ehrenberg (1847, loc. cit., p. 53) they represent one part of his Haliommatina (with four genera, Haliomma, Chilomma, Stylosphæra, Spongosphæra). Most species, however, of these genera are Discoidea. Also in the latest system of Ehrenberg (1875, loc. cit., p. 157) his Haliommatina are a confused conglomeration of different Spumellaria (Sphæroidea, Discoidea, and Prunoidea).

The section Sphæroidea is the largest division of Sphærellaria, comprising not less than one hundred and seven genera and six hundred and fifty species. This enormous number (easily to be augmented by further investigations) requires a careful disposition in different families and subfamilies. For this disposition two different principles only can be employed: firstly, the number and disposition of the radial spines; secondly, the number of the concentric latticed spheres, which are connected by radial beams. I give here the preference to the first principle, whilst in my Prodromus (1881) I had preferred the second. The question, which of the two principles is more important for the classification of Sphæroidea, is very difficult to answer; probably in many cases the former, in many the latter is more important for their phylogeny.

Regarding the number of the concentric shells which compose the latticed carapace of the Sphæroidea, we can distinguish six families, viz.:—

VIII. Monosphærida (with one single shell).
VIII. Dyosphærida (with two concentric shells).
VIII. Triosphærida (with three concentric shells).
IIIV. Tetrasphærida (with four concentric shells).
IIIV. Polysphærida (with five or more concentric shells).
IIVI. Spongosphærida (with spongy shells).

On the other hand, regarding the number of the radial spines and their regular disposition on the shell-surface, we can distinguish five families, viz.:—

VIII. Liosphærida (without radial spines).
VIII. Stylosphærida (with two radial spines, opposite in one axis).
VIII. Staurosphærida (with four radial spines, opposite in pairs in two axes, perpendicular one to another).
IIIV. Cubosphærida (with six radial spines, opposite in pairs in the three dimensive axes).
IIIV. Astrosphærida (with numerous—eight, twelve, twenty, or more—radial spines, often more than a hundred).

All five latter groups contain representatives of all six former groups; therefore we get together not less than thirty different subfamilies of Sphæroidea, already enumerated in my Prodromus, 1881, p. 449. I repeat them here to give a better survey of the system there employed.

Families and Subfamilies of SPHÆROIDEA.	Liosphærida (anacantha).	Stylosphærida (diacantha).	Staurosphærida (tetracantha).	Cubosphærida (hexacantha).	Astrosphærida (polyacantha).
Monosphærida. (One single shell.)	Ethmosphærida.	Xiphostylida.	Staurostylida.	Hexastylida.	Coscinommida.
Dyosphærida. (Two concentric shells.)	Carposphærida.	Sphærostylida.	Staurolonchida.	Hexalonchida.	Haliommida.
Triosphærida. (Three concentric shells.)	Thecosphærida.	Amphistylida.	Stauracontida.	Hexacontida.	Actinommida.
Tetrasphærida. (Four concentric shells.)	Cromyosphærida.	Cromyostylida.	Staurocromyida.	Hexacromyida.	Cromyommida.
Polysphærida. (Five or more concentric shells.)	Caryosphærida.	Caryostylida.	Staurocaryida.	Hexacaryida.	Arachnommida.
Spongosphærida. (Spongy shells.)	Plegmosphærida.	Spongostylida.	Staurodorida.	Hexadorida.	Spongiommida.

The Monosphærida comprise all those Sphæroidea in which the carapace is represented only by one single lattice-shell. Originally this shell is probably everywhere an extracapsular or "cortical shell," which is developed on the outside of the jelly-veil enveloping the central capsule, and serves as a protective carapace for these soft enclosed parts. But with the progress of growth the central capsule becomes larger than the including shell, and sends out through its pores club-shaped prolongations or cæcal-sacs (Pl. 11, figs. 1, 5; Pl. 19, figs. 2, 3, 5; Pl. 20, fig. 1a; Pl. 27, fig. 3). These protruded sacs may fuse together again outside the shell and form a spherical bladder, now enveloping the smaller shell; the latter now becomes an intracapsular or "medullary shell."

As Pliosphærida (or Sphæroidea concentrica) we can oppose to the simple Monosphærida all other Sphæroidea, the lattice-shell of which is composed of two or more concentric shells, connected by radial beams. Probably all Pliosphærida (or at least the greater part of them) arise from the Monosphærida by centrifugal growth; two or more radial spines are developed from the surface of the simple lattice-sphere, and are united together by communicating lateral branches, developed at equal distances from the centre; and this same process may be repeated, two, three, four, or more times. In this way originate the characteristic systems of concentric spheres, all united by piercing radial beams which arise from the surface of the innermost sphere (not from its centre). Regarding this mode of growth, we can distinguish the innermost as "original" or "primary" shell, and all subsequent ones as "apposed" or "secondary" shells; if the number of concentric shells amount to three or more, commonly both innermost shells lie within the central capsule and are medullary shells, whilst all others lie outside it and are therefore cortical shells. This difference can be commonly recognised also in the isolated shell, without its central capsule; the distance between the cortical and the medullary shells being commonly much larger than the distance between the two medullary shells.

The Dyosphærida, or the Sphæroidea with two concentric shells, are the most numerous among the Pliosphærida. Commonly in this group the inner or primary shell lies within the central capsule as a true "medullary shell," whilst the outer lies outside it as a "cortical shell"; therefore the radial beams, connecting both, pierce the wall of the capsule. But in several forms, mainly in the peculiar group of Diplosphærida, both concentric shells remain outside the central capsule, and both are therefore "cortical shells."

The Triosphærida, or the Sphæroidea with three concentric shells, are also very rich in different forms, though not so numerous by far as the Dyosphærida. Commonly in the Triosphærida both inner shells lie within the central capsule as "medullary shells," whilst the third lies outside it as a "cortical shell"; therefore the central capsule remains intermediate in size between the outer and the middle shell. But in some genera (e.g., Rhodosphæra) both outer shells are cortical and only the is a medullary shell. In this case the size of the capsule remains intermediate between the inner and the middle shell.

The Tetrasphærida, or the Sphæroidea with four concentric shells, are in general not frequent, and not rich in different forms. In most of the observed species two inner shells are medullary, two outer cortical shells, the former within, the latter without, the central capsule; and the wall of the capsule, pierced by the connecting radial beams, lies between the two middle shells. But there are some Tetrasphærida in which all four shells seem to be external or cortical shells.

The Polysphærida, or the Sphæroidea with five or more concentric shells, seem of course to offer the greatest possibility for the development of very different forms; but in reality this group is the poorest and smallest of all; and only one part of it, the Arachnosphærida, is rather common. In this peculiar division the shell is composed of five to ten or more, very delicate, cobweb-like concentric shells, which are connected by radial beams; all are cortical shells, and lie outside the central capsule. Much more rare are those Polysphærida, in which both innermost shells, as true medullary shells, lie within the central capsule, all others being outside it. The total number of concentric shells in this group is commonly between five and ten, rarely more.

The Spongosphærida are distinguished from all other Sphæroidea by the spongy structure of the spherical shell, which is composed wholly or partially of an irregular spongy framework. The relation of this group to the other groups of Sphæroidea is probably rather complicated, for in some Spongosphærida the whole shell is composed of massive spongy reticulation, whilst in others it contains a spherical central cavity, and in a third group this cavity is filled up by one or two concentric lattice-shells, connected by radial beams. Many of these Spongosphærida are very common, and of considerable size.

The Collosphærida form a peculiar separate group of Sphæroidea, distinguished from all others by their social life or aggregation in colonies (cœnobia). They represent the only group of Sphærellaria in which this association of numerous individual capsules or cells is realised. The shell is almost constantly simple, without regularly disposed radial spines; therefore they may be called "social Monosphærida," or better "polyzoic Ethmosphærida." Only in one small group (Clathrosphærida) the shell, enveloping every central capsule, is double or surrounded by an external mantle; these may be compared to the Diplosphærida (or better to a part of the Carposphærida, Liosphæra, p. 76). In most of the Collosphærida the lattice-shell is more or less irregular in form and structure.

The Lattice Work of the fenestrated shells is in the Sphæroidea of the greatest variability, and its innumerable modifications serve mainly for the distinction of species. In general we can distinguish as the most important modifications a regular network (with equal size, form, and distance of the pores or meshes) and an irregular network (with differences in the size, form, or distance of the meshes or pores). In both groups the pores may be either angular or round; so that there may exist together four different main forms of network—(A) regular lattice with equal hexagonal pores; (B) regular lattice with equal circular pores; (C) irregular lattice with unequal polygonal pores; (D) irregular lattice with unequal roundish pores. Besides these modifications, the pores may be prolonged into tubules which are directed radially towards the outside (rarely towards the inside) of the sphere. In other cases they are surrounded by elevated or honeycomb-like frames.

The Radial Spines exhibit in the Sphæroidea the greatest variety in form, size, disposition, &c., and their numerous modifications serve mainly for the distinction of genera, their peculiar formation and size also for the distinction of species. In general we may distinguish as the most important modifications primary and secondary spines. The primary spines or "main spines" are commonly direct outward prolongations of the internal radial beams, connecting the concentric shells. The secondary or "by-spines" arise only from the surface of the lattice-shell, without reference to the internal beams. The by-spines are commonly smaller, and much more numerous than the main spines. Regarding the form, the radial spines are either roundish (cylindrical or conical, often also club-shaped, rarely spindle-shaped) or angular (commonly three-sided, prismatic or pyramidal). The spines are constantly solid, never hollow; the "internal canals," described by some authors, are only microscopic views of the transparent edges. In many cases the spines are branched or forked. The most important difference in the variable shape of the spines is their regular or irregular number and disposition, which afford characters for the distinction of our five families.

The Three Dimensive Axes—or the three diameters of the sphere, perpendicular one to another—are in the great majority of the Sphæroidea significant in the promorphological consideration of the body, and are indicated either by the position of the external radial spines, or at least of the internal radial beams, connecting the concentric spheres. Commonly two radial spines are placed opposite in each axis. The most perfect group in this respect seems to be that of the Cubosphærida, in which the three axes are represented by three pairs of spines. Next come the Staurosphærida, in which two axes in cross-form are exhibited by two pairs of spines. The most simple group are the Stylosphærida, in which only one pair of spines is developed, indicating one single axis. These three families form together a continuous natural series,—the Sphæroidea with real dimensive axes,—and exhibit at the same time relations to the three other suborders of Sphærellaria, the Larcoidea, Discoidea, and Prunoidea respectively. At both ends of this series stand two other families, on one side the Liosphærida, without any radial spines on the surface of the sphere, on the other side the Astrosphærida, in which the radial spines are developed in great and variable numbers, at least eight to twelve, commonly twenty to forty, often more than a hundred or even a thousand.

The Liosphærida comprise all those Sphæroidea in which the surface of the shell is smooth, without radial spines (Pls. 12, 20). The simplest of these are the Ethmosphærida, with one single lattice-shell, enveloping the spherical central capsule. Cenosphæra, the most simple form of the Ethmosphærida, may be regarded as the common ancestral form of all Sphæroidea, in an ontogenetical as well as in a phylogenetical and morphological sense. From this simple lattice sphere all other Sphæroidea can be derived either by radial or by tangential growth. If the radial beams, arising from the surface of the simple fenestrated sphere, become connected (at equal distances from the centre) by tangential beams, we get the compound shells of the "Liosphærida concentrica" (with two, three, four, or more concentric spheres). The radial beams connecting these exhibit in many Liosphærida the same regular disposition and number as the external radial spines in the Astrosphærida. Perhaps these forms in a "natural system" would be better united (e.g., Liosphærida with twelve or twenty internal radial beams, and Astrosphærida with twelve or twenty external radial spines); but in many cases (mainly for higher numbers) the certain determination of their number and disposition is very difficult or quite impossible.

The Cubosphærida (Pls. 21-25) represent the large and very important family of Sphæroidea, in which all three dimensive axes are equally distinguished by pairs of spines, corresponding to three axes of a cube or of a regular octahedron, agreeing therefore also with the three axes of the cubic or regular crystalline system. In the majority of the Cubosphærida the six radial spines are accurately opposite each other in pairs in three axes, perpendicular one to another, and commonly they are of equal size and form; but in some genera the three pairs of spines become differentiated, whilst both spines of each pair remain equal. Either one pair is larger than the two others (which are equal), corresponding to the axes of the quadratic crystalline system; or all three pairs are different (corresponding to the three unequal axes of the rhombic crystalline system); the former nearer to the Discoidea, the latter to the Larcoidea. We may suppose with some probability, that the Cubosphærida are for the most part the common ancestral group of those Sphæroidea, in which a certain number of radial spines or beams is disposed in a regular order; the Staurosphærida may be derived from them by loss of one pair of spines, the Stylosphærida by loss of two pairs of spines, and most Astrosphærida by multiplying the radial spines, six to fourteen or more secondary spines being added to the six primary "dimensive spines." However, in many Astrosphærida (e.g., in those with eight spines, Centrocubus, Octodendron, &c.) the regular geometrical disposition of the radial spines seems to follow another mathematical order, quite independent of the Cubosphærida.

The Staurosphærida (Pl. 15) are distinguished by the possession of four radial spines, opposite in pairs in two axes, perpendicular one to another. This rectangular cross determines a certain plane, the "equatorial plane," and this brings the Staurosphærida near to the Discoidea, mainly to those which also bear on the periphery of the circular equatorial plane four crossed spines (such as Staurodisculus, Stethostaurus, Staurodictya, &c.). But in these cruciform Discoidea the shell and the enclosed central capsule are discoidal or lenticular, whilst in the Staurosphærida they remain spherical. Commonly the cross is quite regular, with four right angles and four equal beams; but often also it becomes more or less irregular. In some genera one pair of equal opposite spines is larger than the other pair. These forms represent the three different axes of the rhombic crystal system, whilst the common regular Staurosphærida represent those of the quadratic crystal system. The latter can be derived from the Cubosphærida (representing the regular crystal system) by reduction of one axis and loss of its pair of spines. In general the number of species (and particularly of the individuals) is much smaller in the Staurosphærida than in all other families of Sphæroidea.

The Stylosphærida (Pls. 13-17) can be derived from the Cubosphærida by reduction of two dimensive axes and loss of two pairs of spines. Therefore, here one pair of spines only is developed, opposite in one single axis. This "monaxonial" form brings the Stylosphærida very near to the ellipsoidal Prunoidea (mainly to many two-spined forms of Ellipsida and Druppulida); but they differ from these by the spherical (not ellipsoidal) form of the central capsule and of the enclosing lattice-shell. In the greater part of the Stylosphærida both spines are of equal size and form, accurately opposite in the "main axis." But in many forms both spines become unequal in size or form, often very different. More rarely they are not accurately opposed, but placed in two different axes, intersecting at a small variable angle. The small group of Saturnalida presents a very remarkable and peculiar structure, in which both spines (at equal distances from the centre) are united by a circular or elliptical ring (Pl. 13, figs. 15, 16; Pl. 16, figs. 16, 17).

The Astrosphærida are distinguished from the other Sphæroidea by the great and variable number of their external radial spines (Pls. 11, 18-20, 26-30). Commonly this number amounts to from twelve to twenty, rarely to only eight to ten, very often to thirty-two to forty or more; in many species more than one hundred are present. As already mentioned above, it would be important to distinguish between primary spines (as outer prolongations of the inner radial beams) and secondary spines (developed from the surface of the shell), but in many cases this distinction is difficult or impossible. More practical is the distinction between larger "main spines" and smaller "by-spines." The size and form of the radial spines is extremely variable. Much more important is their number and disposition. In general we can here distinguish the following different cases:—(A) radial spines are developed from all the nodal points of the network on the shell surface; (B) the number of the spines is smaller than that of the nodal points, but they are irregularly scattered; (C) the radial spines exhibit a limited number and a certain regular disposition. In this latter case the following modes of distribution seem to be the most important:—(a) eight spines placed in the four diagonal axes of the regular cube (Pl. 18, figs. 1-3); (b) twelve spines (placed in the corner axes of the regular icosahedron); (c) fourteen spines (six placed in the three dimensive axes of the regular octahedron, eight in the centres of its eight faces); (d) twenty spines (placed either in the same order as in many Larcoidea and Acantharia [?], or in the twenty corners of the regular dodecahedron); (e) thirty-two spines (twelve placed in the twelve corners of the regular icosahedron, twenty in the centre of its triangular faces). Besides these most important and quite geometrical modes of disposition there also seem to occur in the Astrosphærida the following subregular (or symmetrical?) modes: 9, 10, 16, 18, 24, 40, 60, 80. But it is very difficult to give a correct account of these modes. In every case this manifold and regular disposition of the radial spines is of the highest interest for the study of general "Promorphology."

The Central Capsule is in all Sphæroidea (without any exception) a perfect sphere in the geometrical sense, even in those forms in which the enclosing lattice-shell is more or less irregular (i.e., many Collosphærida). This is the most important character, which separates the Sphæroidea from all other Sphærellaria. For in the Prunoidea the capsule is ellipsoidal, with one prolonged axis; in the Discoidea lenticular, with one shortened axis; in the Larcoidea lentelliptical, with three different dimensive axes. The central capsule is originally always enclosed by the lattice-shell; but in many cases with increasing growth this relation becomes inverted; the capsule sending out many club-shaped blind sacs through the meshes of the lattice-shell, and these melting together outside the latter, a new membrane is formed, enclosing a "medullary shell."

The Nucleus of the cell exhibits a very different shape in the solitary and the social Sphæroidea. In the solitary or monozoic Sphæroidea the centre of the central capsule is occupied by a large spherical concentric nucleus, with or without nucleoli; also this nucleus is originally always within the innermost lattice-shell, but with increasing size may overgrow and enclose it. A short time before the formation of the vibratile spores the central nucleus becomes resolved into many small nuclei. In the social or polyzoic Sphæroidea—the Collosphærida—commonly the simple central nucleus very early (a long time before the formation of the spores) is divided into a great number of small nuclei, whilst the centre of the capsule becomes filled with a large oil-globule. Therefore we find the same difference between the solitary and social forms in the Sphæroidea as in the Colloidea. Here also the calymma, or the jelly-mantle, enveloping the central capsule, is in the social forms very large and voluminous, differentiated into alveoles, whilst in the solitary forms it is much smaller, without alveoles.

Synopsis of the Families of Sphæroidea.

Surface of the spherical shell smooth, rough, or thorny, but not armed with radial spines.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A. Liosphærida monozoa. Single cells (each with shell) living solitary.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Spherical shell commonly quite regular, simple, or composed of two or more concentric spheres,	05. Liosphærida.
		B. Liosphærida polyzoa. Aggregated cells (each with shell) living in colonies.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Spherical shell commonly more or less irregular, simple (rarely composed of two concentric spheres),	06. Collosphærida.
Surface of the spherical shell armed with two, four, or six radial main spines, opposite in pairs in one, two, or three dimensive axes (always solitary).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Two radial main-spines, opposite in one axis of the shell			07. Stylosphærida.
		Four radial main-spines, opposite in pairs in two dimensive axes, perpendicular one to another,			08. Staurosphærida.
		Six radial main-spines, opposite in pairs in three dimensive axes (perpendicular one to another),			09. Cubosphærida.
Surface of the spherical shell covered with numerous (commonly irregularly disposed) radial spines, often also twelve to twenty, more or less regularly disposed,					10. Astrosphærida.

Family V. Liosphærida, Haeckel, 1881.

Liosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea without radial spines on the surface of the spherical shell; living solitary (not associated in colonies).

The family Liosphærida comprises all those solitary Sphæroidea in which the surface of the spherical shell is not armed with radial spines. Nearly the half of this large group is formed by the Ethmosphærida, in which the carapace is a quite simple, spherical lattice-shell; this subfamily is probably the common ancestral group from which all other Sphæroidea, or even all Sphærellaria, can be derived in a phylogenetical as well as in a morphological sense. The central capsule in this first subfamily is constantly enclosed by the fenestrated shell, and separated from it by the jelly-veil. The shell is therefore an extracapsular or medullary shell.

To these simple Ethmosphærida all other subfamilies can be opposed as "Liosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells; two in the Carposphærida, three in the Thecosphærida, four in the Cromyosphærida, five or more in the Caryosphærida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated shells. In a sixth subfamily, in the Plegmosphærida, the shell is wholly or partially composed of spongy wicker-work, with or without a latticed medullary shell in the centre.

The internal radial beams, in the "Liosphærida composita" connecting the concentric spheres, exhibit in their number and disposition similar important differences, such as the external radial spines in the Astrosphærida. The following eight different cases of regular disposition were observed:—(A) two opposite beams in one axis; (B) four beams, opposite in pairs in two axes perpendicular one to another; (C) six beams, opposite in pairs in the three dimensive axes; (D) eight beams, opposite in pairs in the four diagonals of the regular cube; (E) twelve beams corresponding to the twelve axes of the regular icosahedron; (F) fourteen beams quite regularly disposed (six corresponding to the three axes of the regular octahedron, eight to the central points of its faces); (G) twenty beams (probably corresponding to the twenty corners of a regular dodecahedron); (H) thirty-two beams, regularly disposed. Rarely the number of the radial beams is intermediate between these eight cases, and rarely it is higher; then commonly the disposition is irregular. The regularity of their disposition in the great majority of cases is very remarkable and evident.

Synopsis of the Genera of Liosphærida.

I. Subfamily Ethmosphærida. (Shell one single latticed sphere.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Pores of the shell simple, not prolonged into free tubuli.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell cavity simple,	15. Cenosphæra.
				Shell cavity with radial beams united in the centre,	16. Stigmosphæra.
		Pores prolonged into free conical or cylindrical tubuli.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Tubuli external, centrifugal,	17. Ethmosphæra.
				Tubuli internal, centripetal,	18. Sethosphæra.
II. Subfamily Carposphærida. (Two concentric spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	One shell medullary (intracapsular), the other cortical (extracapsular),			19. Carposphæra.
		Both shells cortical (near together),			20. Liosphæra.
III. Subfamily Thecosphærida. (Three concentric spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Two shells medullary (intracapsular), one shell cortical (extracapsular),			21. Thecosphæra.
		One shell medullary (intracapsular), two shells cortical (extracapsular),			22. Rhodosphæra.
IV. Subfamily Cromyosphærida. (Four concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Two inner medullary shells (intracapsular), and two outer cortical shells (extracapsular),			23. Cromyosphæra.
V. Subfamily Caryosphærida. (Five or more concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right\}\,}$	Two inner medullary shells, and three or more outer cortical shells,			24. Caryosphæra.
VI. Subfamily Plegmosphærida. (Spherical shell wholly or partially of spongy structure.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Spongy sphere without latticed medullary shell in the centre.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Sphere solid,	25. Styptosphæra.
				Sphere with a central cavity,	26. Plegmosphæra.
		Spongy sphere with one or two latticed medullary shells in the centre.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	One single medullary shell,	27. Spongoplegma.
				Two concentric medullary shells,	28. Spongodictyon.

Subfamily Ethmosphærida,^[1] Haeckel, 1862, Monogr. d. Radiol., p. 348 (sensu restricto).

Definition.—Liosphærida with one single spherical lattice-shell; living solitary, not aggregated in colonies.

Genus 15. Cenosphæra,^[2] Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 237.

Definition.—Liosphærida with one single latticed sphere, with simple shell-pores (not prolonged into free tubuli) and with simple shell-cavity (without internal radial beams).

The genus Cenosphæra is the most simple form of all Sphæroidea, and may be regarded as the common ancestral form of this order. The siliceous latticed shell, in which the central capsule is enclosed, represents a simple regular sphere, with simple cavity. The pores of the shell-wall are simple, not prolonged into radial tubuli (as in Ethmosphæra and Sethosphæra). According to the different form of the pores, the numerous species of this genus can be disposed in four different subgenera. Some species may be easily confounded with isolated shells of the corresponding social Collosphæra; but in this latter the spherical shell-form is commonly more or less irregular, in Cenosphæra quite regular.

Subgenus 1. Phormosphæra, Haeckel, 1881, Prodromus, p. 448.

Definition.—Pores of the shell regular or subregular, hexagonal or circular, with hexagonal frames or lobes; all nearly of equal size and form.

1. Cenosphæra primordialis, n. sp.

Shell very thin walled, smooth. Pores hexagonal, regular, or subregular; twelve to fifteen on the half meridian of the shell; bars between them extremely delicate (only visible when three hundred or four hundred times enlarged). Diameter of the shell nine to ten times that of the meshes. This species is remarkable for the extreme delicacy of the arachnoidal network of the simple spherical shell; it may be regarded as the common ancestral form of all Sphæroidea. The shell equals that of Heliosphæra tenuissima (figured in my Monograph, 1862, pl. ix. fig. 2), but differs from it by the smooth surface and the absence of all spines or thorns. I observed this species living in the Indian Ocean, near Ceylon, in 1882; the spherical diameter of the central capsule is about one-third of that of the shell; the contents of the central capsule are colourless and transparent, except the central dark globular nucleus. The same shells also occur in some mounted preparations of surface organisms from the Challenger.

Dimensions.—Diameter of the shell 0.12, of the pores 0.012.

Habitat.—Indian Ocean, Ceylon, Haeckel; Central Pacific, Stations 266, 271, surface.

2. Cenosphæra inermis, Haeckel.

Heliosphæra inermis, Haeckel, 1862, Monogr. d. Radiol., p. 351, Taf. ix. fig. 1.

Surface of the thin-walled shell smooth. Pores regular, hexagonal, twelve to fifteen times as broad as the bars, seven to nine on the quadrant.

Dimensions.—Diameter of the shell 0.08 to 0.12, pores 0.012 to 0.015, bars 0.001.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

3. Cenosphæra hexagonalis, n. sp.

Surface of the thick-walled shell smooth. Pores regular, hexagonal, five to six times as broad as the bars, six to eight on the quadrant.

Dimensions.—Diameter of the shell 0.1 to 0.15, pores 0.01 to 0.012, bars 0.002.

Habitat.—Central Pacific, Stations 265 to 274, at various depths.

4. Cenosphæra mellifica, n. sp. (Pl. 12, fig. 9).

Surface of the thick-walled shell smooth. Pores regular, circular, with thin hexagonal frames, four times as broad as the bars, six to eight on the quadrant.

Dimensions.—Diameter of the shell 0.2, pores 0.12, bars 0.003.

Habitat.—South Pacific, Station 288, surface.

5. Cenosphæra favosa, n. sp. (Pl. 12, fig. 10).

Surface of the thick-walled shell rough. Pores regular, circular, with thin hexagonal frames, three times as broad as the bars, ten to twelve on the quadrant.

Dimensions.—Diameter of the shell 0.2, pores 0.09, bars 0.003.

Habitat.—North Atlantic, Færöe Channel (Gulf Stream), John Murray, surface.

6. Cenosphæra vesparia, n. sp. (Pl. 12, fig. 11).

Surface of the thick-walled shell smooth. Pores regular, circular, with thick hexagonal frames, twice as broad as the bars, ten to twelve on the quadrant.

Dimensions.—Diameter of the shell 0.25, pores 0.016, bars 0.008.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms, and surface.

7. Cenosphæra bombus, n. sp.

Shell thick walled, rough. Pores regular, circular, with thin hexagonal frames, of the same breadth as the bars, twenty to twenty-two on the quadrant.

Dimensions.—Diameter of the shell 0.3, pores and bars 0.005.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

8. Cenosphæra melecta, n. sp.

Shell thick walled, papillate. Pores regular, circular, double-edged, with thick hexagonal frames, of the same breadth as the bars; a short conical papilla in the corner of each hexagon; fourteen to sixteen pores on the quadrant.

Dimensions.—Diameter of the shell 0.2, pores and bars 0.008.

Habitat.—Fossil in Barbados.

9. Cenosphæra anthophora, n. sp.

Shell thick walled, papillate. Pores regular, circular, with an elegant six-lobed frame and a coronal of six short papillæ; the latter alternating with the six lobes (quite as in Pl. 28, fig. 1b). Pores twice as broad as the bars, ten to twelve on the quadrant.

Dimensions.—Diameter of the shell 0.13, pores 0.01, bars 0.005.

Habitat.—Central Pacific, Station 271, surface.

10. Cenosphæra rosetta, n. sp.

Shell thin walled, smooth. Pores regular, circular, with an elegant six-lobed outer opening, without papillæ. Pores of the same breadth as the bars, six to eight on the quadrant.

Dimensions.—Diameter of the shell 0.1, pores and bars 0.006.

Habitat.—South Atlantic, Station 323, depth 1900 fathoms.

Subgenus 2. Circosphæra, Haeckel.

Definition.—Pores of the spherical shell regular or subregular, circular, without hexagonal frames or lobes, all nearly of equal size and form.

11. Cenosphæra porophæna, Ehrenberg.

Cenosphæra porophæna, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31.

Shell thin walled, smooth. Pores regular, circular, six to eight times as broad as the bars, five to six on the quadrant.

Dimensions.—Diameter of the shell 0.1, pores 0.012, bars 0.002.

Habitat.—Mediterranean (Crete, depth 1100 fathoms; Corfu, surface).

12. Cenosphæra setosa, Ehrenberg.

Cenosphæra setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vii. fig. 1.

Shell thin walled, covered with very short and numerous bristles. Pores regular, circular, five to six times as broad as the bars, six to eight on the quadrant.

Dimensions.—Diameter of the shell 0.17, pores 0.2, bars 0.03.

Habitat.—West Tropical Pacific, 3300 fathoms; Philippine Sea, Station 200, depth 250 fathoms.

13. Cenosphæra plutonis, Ehrenberg.

Cenosphæra plutonis, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B, B. iv. fig. 20.

Shell thin walled, covered with short conical papillæ. Pores regular, circular, twice as broad as the bars, eight to nine on the quadrant.

Dimensions.—Diameter of the shell 0.09, pores 0.006, bars 0.003.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

14. Cenosphæra proserpinæ, n. sp.

Shell thin walled, smooth. Pores regular, circular, four times as broad as the bars, five to six on the quadrant.

Dimensions.—Diameter of the shell 0.08, pores 0.008, bars 0.002.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

15. Cenosphæra eridani, n. sp.

Shell thin walled, smooth. Pores regular, circular, three times as broad as the bars, eleven to twelve on the quadrant.

Dimensions.—Diameter of the shell 0.16, pores 0.01, bars 0.003.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

16. Cenosphæra lethe, n. sp.

Shell thick walled, smooth. Pores regular, circular, double-edged, five times as broad as the bars, sixteen to eighteen on the quadrant.

Dimensions.—Diameter of the shell 0.25, pores 0.01, bars 0.002.

Habitat.—North Atlantic, Station 64, depth 2700 fathoms.

17. Cenosphæra elysia, n. sp. (Pl. 12, fig. 8).

Shell thick walled, rough. Pores regular, circular, double-edged, twice as broad as the bars, twelve to fourteen on the quadrant.

Dimensions.—Diameter of the shell 0.2, pores 0.01, bars 0.005.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

18. Cenosphæra nirwana, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars, twenty-four to twenty-five on the quadrant.

Dimensions.—Diameter of the shell 0.25, pores 0.004, bars 0.002.

Habitat.—Indian Ocean, Belligemma, Ceylon, surface; Haeckel.

19. Cenosphæra maxima, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars, thirty to thirty-three on the quadrant.

Dimensions.—Diameter of the shell 0.3 to 0.4, pores 0.012, bars 0.006.

Habitat.—West Tropical Pacific, Station 225, depth 4475; also fossil in Barbados.

20. Cenosphæra compacta, n. sp. (Pl. 12, fig. 7).

Shell very thick walled, rough (its wall one-fourth to one-third as thick as the radius). Pores subregular, circular, of the same breadth as the bars, seven to eight on the quadrant.

Dimensions.—Diameter of the shell 0.15, pores and bars 0.012.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Cenosphæra radiata, Zittel, 1876 (L. N. 29, p. 84, Taf. ii. figs. 7, 8), a fossil Cretaceous species, is closely allied to Cenosphæra compacta.

21. Cenosphæra crassa, n. sp.

Shell very thick walled, rough (its wall nearly half as thick as the radius). Pores tubular, double-edged, regular, circular, ten times as broad as the thin united bars, twelve to fourteen on the quadrant.

Dimensions.—Diameter of the shell 0.14, pores 0.01, bars 0.001.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

22. Cenosphæra solida, n. sp.

Shell very thick walled, covered with innumerable short bristles (its wall one-third as thick as the radius). Pores regular, circular, four times as broad as the bars, tubular, eight to ten on the quadrant.

Dimensions.—Diameter of the shell 0.2, pores 0.02, bars 0.005.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 3. Cyrtidosphæra, Haeckel, 1862, Monogr. d. Radiol., p. 348.

Definition.—Pores of the spherical shell irregularly polygonal, of unequal size or form, sometimes roundish with polygonal frames.

23. Cenosphæra reticulata, Haeckel.

Cyrtidosphæra reticulata, Haeckel, 1862, Monogr. d. Radiol., p. 349, Taf. xi. fig. 2.

Shell very thin walled, smooth. Pores irregular, polygonal, two to eight times as broad as the bars, fifteen to twenty on the quadrant (groups of four to eight smaller meshes are scattered on the surface, and separated by reticular rows of larger meshes).

Dimensions.—Diameter of the shell 0.16, pores 0.004 to 0.016, bars 0.002.

Habitat.—Mediterranean (Messina), surface.

24. Cenosphæra tenerrima, n. sp.

Shell extremely thin walled, smooth, like a cobweb. Pores very irregular and small, polygonal with thread-like bars, thirty to forty on the quadrant.

Dimensions.—Diameter of the shell 0.25, pores 0.002 to 0.008, bars under 0.001.

Habitat.—Central Pacific, Station 271, surface.

25. Cenosphæra polygonalis, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores, three to four times as broad as the bars, eight to ten on the quadrant.

Dimensions.—Diameter of the shell 0.2, pores 0.012 to 0.02, bars 0.005.

Habitat.—North Pacific, Station 236, surface.

26. Cenosphæra papillata, n. sp.

Shell thick walled, covered with short conical papillæ. Pores irregular, polygonal, three to five times as broad as the bars, fourteen to sixteen on the quadrant.

Dimensions.—Diameter of the shell 0.12, pores 0.004 to 0.007, bars 0.0015.

Habitat.—South Atlantic, Station 325, surface.

27. Cenosphæra cristata, n. sp.

Shell thick walled, rough. Pores irregular, roundish, surrounded by polygonal crested frames two to three times as broad as the bars, eight to twelve on the quadrant.

Dimensions.—Diameter of the shell 0.16, pores 0.006 to 0.01, bars 0.003.

Habitat.—North Pacific, Station 254, surface.

28. Cenosphæra perforata, n. sp. (Pl. 26, fig. 10).

Ceriosphæra perforata, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell thick walled, rough. Pores irregular, roundish, surrounded by high polygonal funnel-shaped frames, which are solid in the inner half, perforated by numerous very small pores in the outer half, sieve-shaped. Pores one to three times as broad as the bars, of very different size, four to six on the quadrant.

Dimensions.—Diameter of the shell 0.15, pores 0.01 to 0.02, bars 0.005 to 0.01.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

29. Cenosphæra coronata, n. sp. (Pl. 26, fig. 11).

Shell thick walled, rough. Pores irregular, roundish, surrounded by high polygonal frames bearing on their sharp crest a series of small papillæ, so that each pore is surrounded by a coronal of such spinules. Pores four to eight times as broad as the bars, four to five on the quadrant.

Dimensions.—Diameter of the shell 0.15, pores 0.01 to 0.03, bars 0.002 to 0.008.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subgenus 4. Porosphæra, Haeckel.

Definition.—Pores of the spherical shell irregular, roundish, without polygonal frames, of unequal size or form.

30. Cenosphæra antiqua, Haeckel.

Cenosphæra plutonis, var., Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 25, Taf. iv. figs. 47, 48. Cenosphæra plutonis, var., Stöhr, 1880, Palæontogr. xxvi. p. 85, Taf. i. fig. 1.

Shell thin walled, smooth. Pores irregular, roundish, two to eight times as broad as the bars, ten to fifteen on the quadrant.

Dimensions.—Diameter of the shell 0.15 to 0.2, pores 0.007 to 0.015, bars 0.002 to 0.008.

Habitat.—Fossil in the Jurassic, Cretaceous, and Tertiary formations; living in the depths of the Atlantic and Pacific; Station 332, depth 2200 fathoms; Station 225, depth 4475 fathoms, &c.

31. Cenosphæra gigantea, n. sp.

Shell thick walled, smooth. Pores irregular, roundish, two to five times as broad as the bars, thirty to forty on the quadrant.

Dimensions.—Diameter of the shell 0.4 to 0.5, pores 0.004 to 0.01, bars 0.002.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

32. Cenosphæra marginata, n. sp.

Shell very thick walled, smooth. Pores irregular, roundish, double-edged, three to eight times as broad as the bars, six to eight on the quadrant.

Dimensions.—Diameter of the shell 0.12, pores 0.01 to 0.03, bars 0.004.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

33. Cenosphæra aspera, Stöhr.

Cenosphæra aspera, Stöhr, 1880, Palæontogr. Bd. xxvi. p. 85, Taf. i. fig. 2.

Shell thick walled, rough, covered with short conical papillæ. Pores irregular, roundish, of about the same breadth as the bars, eight to twelve on the quadrant.

Dimensions.—Diameter of the shell 0.17, pores and bars 0.01 to 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Stöhr.

34. Cenosphæra hirsuta, Ehrenberg.

Cenosphæra hirsuta, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss., Berlin, p. 287, Taf. x. fig. 18.

Shell thin walled, rough, covered with innumerable very short bristles. Pores very irregular, roundish, of about the same breadth as the bars.

Dimensions.—Diameter of the shell 0.11, pores and bars 0.002 to 0.012.

Habitat.—Indian Ocean, Zanzibar, Pullen; depth 2200 fathoms.

Genus 16. Stigmosphæra,^[3] Haeckel, n. gen.

Definition.—Liosphærida with one single latticed sphere, with simple shell-pores (not prolonged into free tubuli); in the central point of the spherical shell-cavity are united a number of radial beams, which become forked and inserted into the inner surface of the shell by their distal ends.

The genus Stigmosphæra differs from Cenosphæra (and from all other Monosphærida) by internal radial beams, which are united in the centre of the simple spherical shell; these beams are branched, and the distal ends of the branches inserted on the internal surface of the shell. I have observed only two, nearly identical specimens of this genus, both with regular, hexagonal pores and thin bars; the beams were implanted in the corners of the hexagons. In one specimen the surface was covered with short radial bristles, whilst these in the other specimen were prolonged into radial spines (like Acanthosphæra). Possibly this peculiar genus is derived from Carposphæra, by reduction and loss of a central medullary shell.

Stigmosphæra actinocentra, n. sp.

Shell very thin walled, rough, with regular circular, hexagonally framed pores, six times as broad as the bars, eight to ten on the quadrant; in the corner of each hexagon a small bristle. In the central point of the shell are united about twelve (?) thin and straight radial beams, which are forked, with dichotomous branches; the distal ends of the branches are inserted in the corners of the hexagons on the inside of the shell.

Dimensions.—Diameter of the shell 0.15, pores 0.02, bars 0.003.

Habitat.—Central Pacific, Station 271, surface.

Genus 17. Ethmosphæra,^[4] Haeckel, 1862, Monogr. d. Radiol., p. 349.

Definition.—Liosphærida with one single latticed sphere, with simple shell-cavity; with shell-pores which are prolonged on the outside in centrifugal, conical, or cylindrical tubuli.

The genus Ethmosphæra differs from the simple Cenosphæra, its ancestral form, by the peculiar formation of the shell-pores; in all observed species of the genus these are quite regular, of nearly equal size and form; their base in the spherical shell-face is hexagonal, but on the outside prolonged into centrifugal, external, radial tubuli, which are either conical or cylindrical (in the latter case both openings of the tubes being equal, in the former the outer opening being smaller than the inner). The solitary Ethmosphæra corresponds to the social Siphonosphæra; but in the former the formation of the shell and of its tubuli is quite regular, in the latter more or less irregular.

Subgenus 1. Ethmosphærella, Haeckel.

Definition.—Tubuli conical, their outer opening smaller than the inner.

1. Ethmosphæra siphonophora, Haeckel.

Ethmosphæra siphonophora, Haeckel, 1862, Monogr. d. Radiol., p. 350, Taf. xi. fig. 1.

Tubuli conical, their outer opening half as broad as the inner and three times as broad as their height. Five to six pores on the quadrant. Diameter of the outer pores one and a half times as large as their distance from each other.

Dimensions.—Diameter of the shell 0.1, outer pores 0.01, their distance 0.007.

Habitat.—Mediterranean (Messina), surface, Haeckel.

2. Ethmosphæra conosiphonia, n. sp. (Pl. 12, figs. 5, 5a).

Tubuli conical, their outer opening two thirds as broad as the inner, and scarcely broader than their height. Ten to twelve pores on the quadrant. Diameter of the outer pores twice as large as their distance from each other.

Dimensions.—Diameter of the shell 0.17, outer pores 0.01, their distance 0.005.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Ethmosphæra polysiphonia, n. sp. (Pl. 12, fig. 6).

Tubuli conical, their outer opening three-fourths as broad as the inner and three times as broad as their height. Sixteen to eighteen pores on the quadrant. Diameter of the outer pores three times as large as their distance apart.

Dimensions.—Diameter of the shell 0.2, outer pores 0.008, their distance 0.003.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados and in Sicily.

Subgenus 2. Ethmosphæromma, Haeckel.

Definition.—Tubuli cylindrical, their outer opening about as large as the inner.

4. Ethmosphæra stenosiphonia, n. sp.

Tubuli cylindrical, short, quite contiguous, so that their diameter is six times as large as their distance apart, but about equal to their height. Nine to ten pores on the quadrant.

Dimensions.—Diameter of the shell 0.14, outer pores 0.012, their distance 0.002.

Habitat.—Central Pacific, Station 271, surface.

5. Ethmosphæra pachysiphonia, n. sp.

Tubuli cylindrical, twice as long as broad, very thick-walled, and nearly contiguous, so that their diameter is five times as large as their distance apart. The thickness of their wall is equal to their lumen. Twelve to fourteen pores on the quadrant.

Dimensions.—Diameter of the shell 0.16, outer pores 0.01, their distance 0.002.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

6. Ethmosphæra leptosiphonia, n. sp.

Tubuli cylindrical, short, about as long as broad, very thin-walled and fragile, separated by wide distances, which are three times as large as their diameter. Six to seven pores on the quadrant. (Very similar to Siphonosphæra cyathina, Pl. 6, fig. 10, but quite regular, all tubuli retaining the same size and distance.)

Dimensions.—Diameter of the shell 0.12, outer pores 0.01, their distance 0.03.

Habitat.—North Atlantic, Færöe Channel, John Murray; surface.

7. Ethmosphæra macrosiphonia, n. sp.

Tubuli cylindrical, very elongated, four times as long as broad; their bases separated by distances which are equal to their breadth. Eight to ten tubuli on the quadrant. (The tubes are similar to those of Siphonosphæra serpula, Pl. 6, fig. 6, but quite regular, straight, not curved, all of the same size and at equal distances apart.)

Dimensions.—Diameter of the shell 0.1, length of the tubes 0.04, breadth 0.01, basal distance 0.01.

Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.

Genus 18. Sethosphæra,^[5] Hæckel, 1881, Prodromus, p. 452 (sensu emendato).

Definition.—Liosphærida with one single latticed sphere, with simple shell-cavity; with shell-pores, which are prolonged on the inside into centripetal, conical, or cylindrical tubuli.

The genus Sethosphæra differs from its ancestral form, Cenosphæra, by the production of internal, centripetal, radial tubuli on the inside of the shell (the contrary of the preceding genus Ethmosphæra). It corresponds therefore to the social Pharyngosphæra; but in the latter the formation of the shell and its tubes is more or less irregular, whilst in the former each regular pore is prolonged into a regular tubule.

1. Sethosphæra entosiphonia, n. sp.

Shell with smooth surface and regular circular pores, separated by hexagonal frames, twice as broad as the bars. Six to eight on the quadrant. Each pore is prolonged on the inside of the shell in a short conical centripetal tube, twice as long as its diameter.

Dimensions.—Diameter of the shell 0.15, outer pores 0.008, bars 0.004, length of the tubuli 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Sethosphæra entosolenia, n. sp.

Shell with smooth surface and regular circular pores, without hexagonal frames, of about the same breadth as the bars. Ten to twelve on the quadrant. Each pore is prolonged on the inside of the shell into a thin cylindrical centripetal tube, three times as long as its diameter.

Dimensions.—Diameter of the shell 0.2, outer pores and bars 0.006, length of the tubuli 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subfamily Carposphærida,^[6] Haeckel, 1881, Prodromus, p. 449.

Definition.—Liosphærida with two concentric spherical lattice-shells, which are united by radial beams.

Carposphæra,^[7] Haeckel, 1881, Prodromus, p. 451.

Definition.—Liosphærida with one medullary (intracapsular) and one cortical (extracapsular) shell, both connected by radial beams piercing the central capsule.

The genus Carposphæra comprises a large number of double-shelled Sphæroidea, formerly united with Haliomma, but different from this genus by the absence of radial spines. The shell is composed of two concentric latticed spheres, the inner of which (or the medullary shell) is situated within the central capsule, the other (or the cortical shell) outside it. Both shells are connected by radial beams which pierce the wall of the central capsule. The distance between the shells is at least as large as (commonly much larger than) the radius of the inner shell, whilst in the following genus, Liosphæra, that distance is much smaller than this radius.

Subgenus 1. Melittosphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.—Pores of the cortical shell regular, hexagonal (or circular, with hexagonal frames or lobes), all of nearly equal size and form.

1. Carposphæra capillacea, n. sp.

Cortical shell very delicate, four times as broad as the similarly constructed medullary shell, with regular hexagonal meshes (twenty to twenty-five on the quadrant) and very thin thread-like bars. Both shells connected by twenty (?) very thin radial beams. (Similar to Heliosoma radians, Pl. 28, fig. 3, 3a, but with smooth surface, without any radial spines.)

Dimensions.—Diameter of the outer shell 0.2, inner 0.05, pores 0.01, bars below 0.001.

Habitat.—Central Pacific, Station 274, surface.

2. Carposphæra cubaxonia, n. sp.

Cortical shell smooth, three times as broad as the medullary shell, with regular hexagonal pores, four times as broad as the bars. Eight to ten pores on the quadrant. Medullary shell with regular circular pores, twice as broad as the bars. Both shells connected by six radial beams, which are three-sided prismatical, opposite in pairs in the three dimensive axes.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; outer pores 0.01, inner 0.005.

Habitat.—South Pacific, Station 291, surface.

3. Carposphæra infundibulum, Haeckel.

Haliomma infundibuliforme, Stöhr, 1880, Palæontogr. Bd. xxvi. p. 87, Taf. i. fig. 6.

Cortical shell very thick-walled, two and a half times as broad as the medullary shell, with rough surface and regular hexagonal, funnel-shaped pores, of about the same breadth as the bars. Five to six on the quadrant.

Dimensions.—Diameter of the outer shell 0.1, inner 0.04, outer pores and bars 0.01.

Habitat.—North Atlantic, Station 354; fossil in Tertiary rocks (Barbados and Sicily).

4. Carposphæra melissa, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with regular circular, hexagonally framed pores, three times as broad as the bars. Eight to ten pores on the quadrant. Medullary shell with simple circular pores.

Dimensions.—Diameter of the outer shell 0.16, inner 0.04, outer pores 0.012, bars 0.004.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Carposphæra melitomma, n. sp. (Pl. 20, fig. 4).

Melitomma melittosphæra, Haeckel, 1881; Prodromus et Atlas, loc. cit.

Cortical shell thick walled, with thorny surface, two and a half times as broad as the medullary shell. Its pores regular, circular, twice as broad as the bars, elegantly six-lobed, separated by crested hexagonal frames; in each hexagon-corner a short conical papilla (alternating with a lobe). Eight to ten pores on the quadrant. Medullary shell with small simple circular pores.

Dimensions.—Diameter of the outer shell 0.17, inner 0.07, outer pores 0.01, bars 0.005, inner pores 0.005.

Habitat.—Central Pacific, Stations 266 to 274, in various depths.

Subgenus 2. Cerasosphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.—Pores of the cortical shell regular, circular, without hexagonal frames, all of nearly equal size and form.

6. Carposphæra cerasus, n. sp.

Cortical shell thin walled, smooth, twice as broad as the medullary shell; both with regular circular pores, six times as broad as the bars. Twelve to fifteen pores on the quadrant. Outer pores twice as large as the inner.

Dimensions.—Diameter of the outer shell 0.24, inner 0.12; outer pores 0.016, inner 0.008.

Habitat.—Central Pacific, Station 271, surface.

7. Carposphæra apiculata, Haeckel.

? Haliomma apiculatum, Ehrenberg, 1872; Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 313.

Cortical shell thin-walled, covered with numerous short conical thorns, three times as broad as the medullary shell. Pores regular, circular, four times as broad as the bars. Six to eight pores on the quadrant.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05, outer pores 0.012, bars 0.03.

Habitat.—North Pacific, California, depth 2000 fathoms; Station 254, depth 3025 fathoms.

8. Carposphæra entactinia, Haeckel.

Haliomma entactinia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxvi. fig. 4.

Cortical shell thick walled, rough, twice as broad as the medullary shell; both shells with regular circular pores, twice as broad as the bars. Six to eight pores on the quadrant. Outer pores half as broad as the inner. Both shells connected by very numerous (twenty-four to forty-eight or more) radial beams.

Dimensions.—Diameter of the outer shell 0.12, inner 0.06, outer pores 0.008, bars 0.004, inner pores 0.004.

Habitat.—Cosmopolitan; Atlantic and Pacific, in various depths; fossil in Barbados and Sicily.

9. Carposphæra modesta, Haeckel.

Haliomma modestum, Stöhr, 1880, Palæontogr. Bd. xxvi. p. 86, Taf. i. fig. 5.

Cortical shell thick walled, rough, three times as broad as the medullary shell, with regular circular pores of the same breadth as the bars. Eight to twelve pores on the quadrant. (Very common, like the preceding species, and connected with it by numerous intermediate forms.)

Dimensions.—Diameter of the outer shell 0.12 to 0.2, inner 0.04 to 0.07, pores and bars 0.006 to 0.008.

Habitat.—Atlantic and Pacific, from many Stations and at various depths; fossil in Barbados and Sicily.

10. Carposphæra belladonna, n. sp.

Cortical shell thick walled, smooth, five times as broad as the medullary shell, with regular circular pores of the same breadth as the bars. Twenty to twenty-two pores on the quadrant.

Dimensions.—Diameter of the outer shell 0.3, inner 0.06, outer pores and bars 0.004.

Habitat.—North Atlantic, Færöe Channel, John Murray.

11. Carposphæra areca, n. sp.

Cortical shell very thick walled, rough, twice as broad as the medullary shell, with regular circular pores half as broad as the bars. Eight to ten pores on the quadrant.

Dimensions.—Diameter of the outer shell 0.12, inner 0.06, outer pores 0.03, bars 0.006.

Habitat.—Indian Ocean, Ceylon, Haeckel, surface.

Subgenus 3. Prunosphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.—Pores of the cortical shell irregular polygonal, of unequal size or dissimilar form.

12. Carposphæra prunulum, n. sp.

Cortical shell thin walled, smooth, four times as broad as the medullary shell, with large irregular polygonal pores, four to eight times as broad as the bars. Connecting beams between them numerous.

Dimensions.—Diameter of the outer shell 0.24, inner 0.06, outer pores 0.008 to 0.016, bars 0.002.

Habitat.—South Atlantic, Station 325, surface.

13. Carposphæra corypha, n. sp.

Cortical shell thin walled, rough, three times as broad as the medullary shell, with irregular polygonal pores, three to six times as broad as the bars. Connecting beams between the two shells twenty, regularly disposed.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05, outer pores 0.01 to 0.02, bars 0.003.

Habitat.—South Pacific, Station 300, surface.

14. Carposphæra borassus, n. sp.

Cortical shell thick walled, smooth, three times as broad as the medullary shell, with irregular polygonal pores, two to four times as broad as the bars. Connecting beams between the two shells six, opposite by pairs in the three dimensive axes. (Similar to Hexalonche aristarchi, Pl. 22, fig. 3, but without external radial spines.)

Dimensions.—Diameter of the outer shell 0.12, inner 0.04, outer pores 0.01 to 0.02, bars 0.005.

Habitat.—Central Pacific, Station 268, surface.

Subgenus 4. Phœnicosphæra, Haeckel.

Definition.—Pores of the cortical shell irregular roundish, of unequal size or form.

15. Carposphæra nobilis, Haeckel.

Haliomma nobile, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 268; Abhandl., 1875, Taf. xxvii. fig. 6.

Cortical shell thin walled, rough, twice as broad as the medullary shell, with irregular roundish pores, two to four times as broad as the bars.

Dimensions.—Diameter of the outer shell 0.1, inner 0.05, outer pores 0.01 to 0.02, bars 0.006.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, at various depths; fossil in Jurassic, Cretaceous, and Tertiary rocks.

16. Carposphæra micrococcus, n. sp.

Cortical shell thin walled, rough, seven times as broad as the medullary shell, with irregular roundish pores, three to six times as broad as the bars.

Dimensions.—Diameter of the outer shell 0.2, inner 0.03, outer pores 0.012 to 0.025, bars 0.004.

Habitat.—South Atlantic, Station 330, surface.

17. Carposphæra maxima, n. sp.

Cortical shell thin walled, smooth, five times as broad as the medullary shell, with irregular roundish pores, of about the same breadth as the bars.

Dimensions.—Diameter of the outer shell 0.4, inner 0.08, pores and bars 0.004 to 0.008.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

18. Carposphæra nodosa, n. sp. (Pl. 28, figs. 2, 2a).

Anthomma nodosum, Haeckel, 1879, Atlas, loc. cit.

Cortical shell thick walled, covered with forty to fifty scattered pyramidal nodules, two and a half times as broad as the medullary shell, connected with it by very numerous thin radial beams. Outer and inner pores irregular roundish or polygonal, two to three times as broad as the bars. (This species in consequence of the cortical nodules may represent a peculiar genus, analogous to Conosphæra, called Anthomma.)

Dimensions.—Diameter of the outer shell 0.13, inner 0.05, inner and outer pores 0.008 to 0.012, bars 0.004.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 20. Liosphæra,^[8] Haeckel, 1881, Prodromus, p. 449.

Definition.—Liosphærida with two cortical (extracapsular) shells (without a medullary or intracapsular shell).

The genus Liosphæra agrees with the preceding Carposphæra in the possession of two concentric latticed spheres; but whilst in the latter genus the inner sphere is a medullary one (intracapsular), the outer a cortical shell (extracapsular), both connected by radial beams piercing the capsule-wall, here in Liosphæra the central capsule lies freely within the inner lattice shell and is not pierced by radial beams. Therefore both shells are here cortical shells, both separated by a distance, which is constantly much smaller than the radius of the inner shell; whereas in Carposphæra this distance is at least as large as that radius (commonly much larger). In Carposphæra the number of pores in both shells is never the same; in several species of Liosphæra this number is the same, each outer regular hexagonal pore exactly corresponding to an inner; the six corners of each connected by six short radial beams.

Subgenus 1. Melitomma, Haeckel.

Definition.—Pores of both shells regular, in each shell all of nearly equal size and form.

1. Liosphæra hexagonia, n. sp. (Pl. 20, fig. 3).

Both shells with the same number of pores, exactly corresponding, about ten on the quadrant. All pores regular, or subregular, hexagonal; the outer twice as broad as the inner. Outer bars very thin, thread-like; inner bars thick, one-third as broad as the pores. Surface smooth. Both shells connected by numerous radial beams, their distance one-third as large as the radius of the inner shell.

Dimensions.—Diameter of the outer shell 0.16, inner 0.12, distance of both 0.02; outer pores 0.014, inner pores 0.007.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Liosphæra rhodococcus, n. sp.

Both shells with the same number of pores, exactly corresponding, about twelve on the quadrant. All pores regular or subregular; the inner circular, with elegant six-lobed frames, twice as broad as the bars; the outer hexagonal, with very thin thread-like bars. All corners of the outer and inner hexagons connected by thin, bristle-shaped radial beams. (Similar to Haliomma rhodococcus, Pl. 19, fig. 6; but with smooth surface and regular hexagonal pores of the outer shell.)

Dimensions.—Diameter of the outer shell 0.2, inner 0.16, distance of both 0.02; outer pores 0.03, inner 0.01.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Liosphæra porulosa, n. sp.

Both shells with regular hexagonal pores; their number in the outer shell seven times as great as in the inner. Pores of the stout inner shell large, three times as broad as the bars, about eight on the quadrant. From each hexagon-corner arises one bristle-shaped radial beam; their distal ends are united by threads (three from each), forming the large meshes of the delicate outer shell. Each of these is divided by very thin threads into seven small circular porules, one central and six around it.

Dimensions.—Diameter of the outer shell 0.25, inner 0.2, distance of both 0.025; outer pores 0.04, their porules 0.012, inner pores 0.15.

Habitat.—Indian Ocean, Sunda Strait, Rabbe; surface.

Subgenus 2. Craspedomma, Haeckel.

Definition.—Pores of both shells irregular, in each shell differing either in form or size.

4. Liosphæra peridromium, n. sp.

Both shells with the same number of large, polygonal, very irregular pores, exactly corresponding (about eight to ten on the quadrant); both with a very delicate thin framework. From the thread-like bars of the inner, very large and thin-walled, sphere arise perpendicularly innumerable short bristles of equal length, which are united at equal distances by tangential thread-like bars, parallel to the former, composing the outer shell. Each mesh is, therefore, surrounded by a delicate ballister or rail.

Dimensions.—Diameter of the outer shell 0.42, inner 0.4, distance of both 0.01; diameter of the meshes 0.02 to 0.06.

Habitat.—North Pacific, Station 250, surface.

5. Liosphæra polypora, n. sp. (Pl. 20, fig. 2).

Both shells with small irregular roundish pores, of about the same size as the bars between them; twenty to thirty on the quadrant. The pores of the outer shell somewhat smaller, therefore much more numerous than the pores of the inner shell. Distance between the two shells about one-third as great as the radius of the inner. Both shells connected by numerous thin radial beams. Surface smooth or a little rough.

Dimensions.—Diameter of the outer shell 0.18, inner 0.14, distance of both 0.02; pores and bars 0.003 to 0.005.

Habitat.—West Tropical Pacific, Station 225, depth 4475.

Subfamily Thecosphærida,^[9] Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.—Liosphærida with three concentric spherical lattice-shells, which are united by radial beams.

Genus 21. Thecosphæra,^[10] Haeckel, 1881, Prodromus, p. 452.

Definition.—Liosphærida with two medullary (intracapsular) shells and one cortical (extracapsular) shell.

The genus Thecosphæra comprises a large number of triple-shelled Sphæroidea, formerly united with Actinomma, but different from this genus in the absence of radial spines. The latticed shell is composed of three concentric spheres, two of which lie within the central capsule (medullary shells), and one outside (cortical shell). This latter is connected with the former by radial beams piercing the wall of the central capsule. From the following Rhodosphæra (with one medullary and two cortical shells) Carposphæra differs also by the distance of the three shells. In the former the distance between the two outer shells is much smaller, in the latter much larger, than the distance between the inner shells.

Subgenus 1. Thecosphærantha, Haeckel.

Definition.—Pores of the cortical shell regular, hexagonal, or circular, with hexagonal frames or lobes, all of nearly equal size and form.

1. Thecosphæra triplodictyon, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 8. Both medullary shells with regular circular pores, twice as broad as the bars, the inner half as broad as the outer. All three shells connected by six thin radial beams, opposite in pairs in the three dimensive axes.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.025; cortical pores 0.012, bars 0.003.

Habitat.—Central Pacific, Station 271, surface.

2. Thecosphæra phænaxonia, n. sp.

Cortical shell thick walled, rough, with regular, circular, hexagonally framed pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 6. Both medullary shells with regular hexagonal pores and thin bars. All three shells connected by six prismatic radial beams, opposite in pairs in the three dimensive axes. (Shell similar to Hexacontium sceptrum, Pl. 24, fig. 1, 1a, but without external spines.)

Dimensions.—Diameter of the outer shell 0.12, middle 0.04, inner 0.02; cortical pores 0.01, bars 0.005.

Habitat.—North Pacific, Station 253, surface.

3. Thecosphæra favosa, n. sp.

Cortical shell thick walled, thorny, with regular, circular, hexagonally framed pores, of the same breadth as the bars. Radial proportion of the three spheres = 1 : 3 : 10. Both medullary shells with regular circular pores, connected with the former by twelve short prismatic, regularly disposed radial beams.

Dimensions.—Diameter of the outer shell 0.2, middle 0.06, inner 0.02; cortical pores and bars 0.008.

Habitat.—Central Pacific, Station 268, surface; also fossil in Barbados.

4. Thecosphæra floribunda, n. sp.

Cortical shell thick walled, smooth, with regular, elegantly six-lobed pores, three times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Both medullary shells with simple regular circular pores, connected with the former by six dimensive radial beams. (Similar to Hexacontium floridum, Pl. 24, fig. 4, but without external spines.)

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.03; cortical pores 0.01, bars 0.0033.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 2. Thecosphærella, Haeckel.

Definition.—Pores of the cortical shell regular, circular, without hexagonal frames or lobes, all of nearly equal size and form.

5. Thecosphæra inermis, Haeckel.

Actinomma inerme, Haeckel, 1862, Monogr. d. Radiol., p. 440, Taf. xxiv. fig. 5. Haliomma inerme, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 815.

Cortical shell thin walled, rough, with regular circular pores, twice as broad as the bars. Radial proportion of the three spheres and of their circular regular pores = 1 : 2 : 4. All three spheres connected by twelve regularly disposed radial beams.

Dimensions.—Diameter of the outer shell 0.1, middle 0.05, inner 0.025; cortical pores 0.006, bars 0.003.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, at many Stations and at various depths.

6. Thecosphæra æquorea, Haeckel.

Haliomma æquorea, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83; Mikrogeol., 1854, Taf. xxii. fig. 35. Actinomma æquorea, Haeckel, 1862, Monogr. d. Radiol., p. 443.

Cortical shell thick walled, smooth, with regular circular pores of the same breadth as the bars. Radial proportion of the three spheres and of their regular pores = 1 : 2 : 6 or = 1 : 3 : 9; they are connected by six radial beams, opposite by pairs in the three dimensive axes.

Dimensions.—Diameter of the outer shell 0.08 to 0.12, middle 0.03 to 0.04, inner 0.09 to 0.12; cortical pores and bars about 0.006.

Habitat.—Mediterranean, Corfu, surface; fossil in Greece and Sicily.

7. Thecosphæra medusa, Haeckel.

Haliomma medusa, Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 130; Mikrogeol., 1854, Taf. xxii. figs. 33, 34.

Actinomma medusa, Haeckel, 1862, Monogr. d. Radiol., p. 444.

Actinomma medusa, Stöhr, 1880, Palæontogr., Bd. xxvi. p. 90, Taf. ii. fig. 3.

Cortical shell thick walled, rough or thorny, with regular circular pores of the same breadth as the bars. Radial proportion of the three spheres = 1 : 2 : 4 (or 1 : 2.5 : 6); they are connected by four radial beams, crossed by pairs in two diameters, perpendicular one to another.

Dimensions.—Diameter of the outer shell 0.08 to 0.12, middle 0.04 to 0.06, inner 0.02 to 0.025; cortical pores and bars in average 0.005.

Habitat.—Fossil in Tertiary rocks of Barbados and the Mediterranean.

8. Thecosphæra entactinia, n. sp.

Cortical shell thick walled, smooth, with regular circular pores of the same breadth as the bars. Radial proportion of the three spheres = 1 : 3 : 12; they are connected by very numerous (forty to fifty, or more) thin radial beams.

Dimensions.—Diameter of the outer shell 0.24, middle 0.06, inner 0.02; cortical pores and bars 0.008.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

9. Thecosphæra micropora, n. sp.

Cortical shell thin walled, smooth, with very small and numerous, regular, circular pores, half as broad as the bars. Radial proportion of the three shells = 1 : 2 : 5; they are connected by twenty regularly disposed radial beams.

Dimensions.—Diameter of the outer shell 0.2, middle 0.08, inner 0.04; cortical pores 0.002, bars 0.004.

Habitat.—South Pacific, Station 288, surface.

Subgenus 3. Thecosphærina, Haeckel.

Definition.—Pores of the cortical shell irregular polygonal, of unequal size or dissimilar form.

10. Thecosphæra capillacea, n. sp.

Cortical shell thin walled, smooth, with irregular polygonal pores, three to six times as broad as the bars. Both medullary shells with similar, but smaller, pores. Radial proportion of the three spheres = 1 : 3 : 8; they are connected by very numerous (sixty to eighty or more) thin radial beams. (Similar to Actinomma capillaceum, Pl. 29, fig. 6, but without external spines.)

Dimensions.—Diameter of the outer shell 0.2, middle 0.075, inner 0.025; cortical pores 0.006 to 0.012, bars 0.002.

Habitat.—North Pacific, Station 250, surface.

11. Thecosphæra diplococcus, n. sp.

Cortical shell thick walled, rough, with large irregular polygonal pores, two to three times as broad as the bars. Both medullary shells with small regular circular pores. Radial proportion of the three spheres = 1 : 2 : 6; they are connected by twenty (?) stout radial beams.

Dimensions.—Diameter of the outer shell 0.12, middle 0.04, inner 0.02; cortical pores 0.008 to 0.012, bars 0.004.

Habitat.—South Atlantic, Station 330, surface.

Subgenus 4. Thecosphæromma, Haeckel.

Definition.—Pores of the cortical shell irregular, roundish, of unequal size or dissimilar form.

12. Thecosphæra dodecactis, n. sp.

Cortical shell thin walled, smooth, with large irregular roundish pores, two to eight times as broad as the bars. Both medullary shells with regular circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 5; they are connected by twelve regularly disposed stout radial beams.

Dimensions.—Diameter of the outer shell 0.2, middle 0.08, inner 0.04; cortical pores 0.004 to 0.016, bars 0.002.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

13. Thecosphæra icosactis, n. sp.

Cortical shell thin walled, with small irregular roundish pores, two to four times as broad as the bars. Both medullary shells with similar but smaller pores. Radial proportion of the three spheres = 1 : 3 : 8; they are connected by twenty thin radial beams.

Dimensions.—Diameter of the outer shell 0.32, middle 0.12, inner 0.04; cortical pores 0.005 to 0.012, bars 0.003.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

14. Thecosphæra maxima, n. sp.

Cortical shell thin walled, with small irregular roundish pores, two to six times as broad as the bars. Both medullary shells with similar, but smaller, pores. Radial proportion of the three spheres = 1 : 3 : 9; they are connected by numerous (forty to sixty or more) thin radial beams.

Dimensions.—Diameter of the outer shell 0.45, middle 0.15, inner 0.05; cortical pores 0.008 to 0.024, bars 0.004.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 22. Rhodosphæra,^[11] Haeckel, 1881, Prodromus, p. 452.

Definition.—Liosphærida with one medullary (intracapsular) shell and two cortical (extracapsular) shells.

The genus Rhodosphæra differs from the preceding Thecosphæra in the same manner in which, among the Dyosphærida, Liosphæra differs from Carposphæra. The cortical shell is double, composed of two not far distant shells, lying outside the central capsule. The distance between the shells is much smaller than the radius of the inner shell. This is connected by radial beams (piercing the central capsule) with the small central medullary shell.

Subgenus 1. Rhodosphærella, Haeckel.

Definition.—Pores of both cortical shells regular, in each shell all of nearly equal size and form.

1. Rhodosphæra hexagonia, n. sp.

Both cortical shells with the same number of regular hexagonal pores; the inner four times as broad as the bars, and half as broad as the outer pores, which are separated by thread-like bars. Medullary shell only one-fourth as broad as the inner cortical shell, with regular hexagonal pores of half the size. (Differs from the similar Liosphæra hexagonia, Pl. 20, fig. 3, by the possession of a medullary shell.)

Dimensions.—Diameter of the outer shell 0.2, middle 0.16, inner 0.04; outer pores 0.013, middle 0.008, inner 0.004.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Rhodosphæra melitomma, n. sp.

Both cortical shells with the same number of regular pores; the inner regular, circular, twice as broad as the bars, with elegant hexagonal frames and six roundish lobes alternating with the six radial spines which arise from the hexagon-corners; these short conical spines are connected at the distal end (at equal distances from the centre) by delicate threads (three from each spine), which form the delicate external shell. Medullary shell one-third as broad as the inner cortical shell, with small, simple, regular circular pores. (If in Carposphæra melitomma, Pl. 20, fig. 4, the distal ends of the spines became united by a cobweb-like outer shell, this species would be formed.)

Dimensions.—Diameter of the outer shell 0.22, middle 0.18, inner 0.06; outer pores 0.025, middle 0.0125, inner 0.005.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Subgenus 2. Rhodosphæromma, Haeckel.

Definition.—Pores of both cortical shells irregular, in each shell of unequal size or dissimilar form.

3. Rhodosphæra palliata, n. sp.

Both cortical shells with an unequal number of irregular roundish pores; the outer pores somewhat smaller and much more numerous than the inner pores; the bars between the latter are thicker. Medullary shell about one quarter as broad as the inner cortical shell, with regular circular pores.

Dimensions.—Diameter of the outer shell 0.4, middle 0.36, inner 0.08; outer pores on an average 0.008, middle 0.012, inner 0.004.

Habitat.—Fossil in Barbados.

4. Rhodosphæra pentaphylla, n. sp.

Both cortical shells with unequal number of irregular roundish pores; the inner pores large, three to four times as broad as the bars; to each inner pore corresponds a group of five smaller outer pores, like the five petals of a flower. Medullary shell half as broad as the inner cortical shell, with regular circular pores.

Dimensions.—Diameter of the outer shell 0.25, middle 0.2, inner 0.1; outer pores on an average 0.006, middle 0.012, inner 0.004.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subfamily Cromyosphærida,^[12] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Liosphærida with four concentric spherical latticed shells, united by radial beams.

Genus 23. Cromyosphæra,^[13] Haeckel, 1881, Prodromus, p. 453.

Definition.—Liosphærida with two intracapsular (medullary) shells and two extracapsular (cortical) shells; the former united with the latter by radial beams piercing the wall of the central capsule.

The genus Cromyosphæra is the only known genus of Cromyosphærida, or of such Sphæroidea, the smooth shell of which is composed of two medullary and two cortical shells. There may possibly be other Cromyosphærida, in which the shell is composed of one simple medullary and three cortical shells, or only of four extra-capsular cortical shells; but such have not as yet been observed. Caryosphæra polysphærica, Bütschli, 1882 (L. N. 41, Taf. xxiii. fig. 12) is probably a Cromyosphæra (fossil in Barbados).

1. Cromyosphæra quadruplex, n. sp. (Pl. 30, fig. 9).

Radial proportion of the four spheres = 1 : 2 : 4 : 5. Outer cortical shell smooth, with large regular hexagonal pores, ten times as broad as the bars; inner cortical shell with irregular polygonal pores, five times as broad as the bars. Both medullary shells with regular circular pores of the same breadth as the bars.

Dimensions.—Diameter of the four spheres—(A) 0.16, (B) 0.12, (C) 0.06, (D) 0.03.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Cromyosphæra rosetta, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Outer cortical shell smooth, with regular hexagonal pores and very thin bars; inner cortical shell with the same number of exactly corresponding, regular circular, hexagonally framed pores, twice as broad as the bars; the corners of the outer and inner hexagons united by radial bristles. Both medullary shells with regular circular pores, twice as broad as the bars.

Dimensions.—Diameter of the four spheres—(A) 0.2, (B) 0.16, (C) 0.04, (D) 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Cromyosphæra bigemina, n. sp.

Radial proportion of the four spheres = 1 : 2 : 7 : 8. Outer cortical shell smooth, with regular hexagonal pores and very thin bars; inner cortical shell with the same number of exactly corresponding, regular circular pores. Both medullary shells with regular circular pores of the same breadth as the bars. (Somewhat similar to Hexacromyon elegans, Pl. 24, fig. 9, also with six inner radial beams, but without external radial spines.)

Dimensions.—Diameter of the four spheres—(A) 0.2, (B) 0.17, (C) 0.05, (D) 0.025.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Cromyosphæra cepa, n. sp.

Radial proportion of the four spheres = 1 : 2 : 4 : 5. All four shells of the same structure, thick-walled, with regular circular pores, two to four times as broad as the bars; the size of the pores increases gradually from the inner to the outer shell. Surface thorny. Distance between the second and third shells twice as great as that between the others.

Dimensions.—Diameter of the four spheres—(A) 0.125, (B) 0.1, (C) 0.05, (D) 0.025.

Habitat.—Fossil in Barbados.

5. Cromyosphæra scorodonium, n. sp.

Radial proportion of the four spheres = 1 : 2 : 3 : 4. All four shells of the same structure, thin-walled, with irregular roundish pores, two to four times as broad as the bars; the size of the pores increasing gradually from the inner to the outer shell. Surface smooth. Distance between each two shells equal to the diameter of the innermost.

Dimensions.—Diameter of the four spheres—(A) 0.12, (B) 0.09, (C) 0.06, (D) 0.03.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

6. Cromyosphæra antarctica, n. sp..

Radial proportion of the four spheres = 1 : 2 : 5 : 7. Both cortical shells with irregular polygonal roundish pores; the outermost with thinner bars and rough surface, the inner with thicker bars. Both medullary shells with irregular roundish pores.

Dimensions.—Diameter of the four spheres—(A) 0.18, (B) 0.12, (C) 0.05, (D) 0.025.

Habitat.—Antarctic Ocean; in very large number, together with Rhizosphæra antarctica, in the diatomaceous ooze of Station 157 (3rd March 1874); depth 1950 fathoms.

Subfamily Caryosphærida,^[14] Haeckel, 1881, Prodromus, pp. 449, 454.

Definition.—Liosphærida with numerous (five or more) concentric spherical latticed shells, united by radial beams.

Genus 24. Caryosphæra,^[15] Haeckel, 1881, Prodromus, p. 454.

Definition.—Liosphærida with two intracapsular (medullary) shells and three or more extracapsular (cortical) shells; the former united with the latter by radial beams piercing the wall of the central capsule.

The genus Caryosphæra, the only observed form of this subfamily, comprises those Liosphærida in which the shell is composed of two medullary and three or more cortical shells. Such forms (without radial spines) are very rare; I observed only two species, one with five, the other with six shells. They are derived from Cromyosphæra by further apposition of outer cortical shells.

1. Caryosphæra pentalepas, n. sp.

Shell composed of five concentric spheres, with radial proportion = 1 : 2 : 8 : 10 : 12. Both medullary shells with regular circular pores, twice as broad as the bars. First cortical shell with regular, circular, hexagonally framed pores, three times as broad as the bars; second cortical shell with regular hexagonal pores, four times as broad as the bars; third (outermost) cortical shell with regular hexagonal pores and very thin thread-like bars. Surface smooth.

Dimensions.—Diameter of the five shells—(A) 0.02, (B) 0.04, (C) 0.16, (D) 0.2, (E) 0.24.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Caryosphæra hexalepas, n. sp.

Shell composed of six concentric spheres, with the radial proportion = 1 : 2 : 4 : 5 : 6 : 8. All six shells with regular circular pores, two to four times as broad as the bars, with increasing size from the centrum against the smooth surface.

Dimensions.—Diameter of the six shells—(A) 0.025, (B) 0.05, (C) 0.1, (D) 0.13, (E) 0.16, (F) 0.2.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

Subfamily Plegmosphærida,^[16] Haeckel, 1881, Prodromus, p. 455.

Definition.—Liosphærida with spongy spherical shell, with or without latticed medullary shell in the centre.

Genus 25. Styptosphæra,^[17] Haeckel, 1881, Prodromus, p. 455.

Definition.—Liosphærida forming a solid sphere of spongy framework, without enclosed medullary shell, and without central cavity.

The genus Styptosphæra presents a spherical shell with smooth or rough surface (without radial spines), the whole mass of which is composed of looser or denser spongy wicker-work.

1. Styptosphæra spumacea, n. sp.

Spongy framework of the solid sphere loose, with large polygonal meshes of slightly different size, ten to twenty times as broad as the bars. Structure of the whole spongy sphere the same. Central capsule filled with crystals. Surface smooth.

Dimensions.—Diameter of the sphere 0.32, of the central capsule 0.26, meshes 0.01 to 0.02, bars 0.001.

Habitat.—North Pacific, Station 236, surface.

2. Styptosphæra spongiacea, n. sp.

Spongy framework in the central part of the solid sphere much more compact than in the peripheral part, becoming gradually looser towards the rough surface. Meshes in the centre three to five times, in the periphery fifteen to twenty times as broad as the bent bars.

Dimensions.—Diameter of the sphere 0.45, inner meshes 0.006 to 0.01, outer meshes 0.03 to 0.04, bars 0.002.

Habitat.—Central Pacific, Station 271, surface.

3. Styptosphæra stupacea, n. sp.

Spongy framework of the solid sphere rather compact, everywhere of the same structure, with roundish, nearly equal meshes, six to eight times as broad as the bars. Surface rough with prominent thorns.

Dimensions.—Diameter of the sphere 0.22, meshes 0.01 to 0.012, bars 0.0015.

Habitat.—South Pacific, Station 291, surface.

Genus 26. Plegmosphæra, Haeckel,^[18] 1881, Prodromus, p. 455.

Definition.—Liosphærida forming a hollow sphere of spongy framework, without a medullary shell in the central cavity.

The genus Plegmosphæra develops a large hollow sphere, the wall of which is composed of looser or denser spongy wicker-work. On the inner as well as on the outer face of the spongy shell-wall may be present a simple lattice-sphere from which the threads of the framework arise; but in some species these lattice-plates are quite absent.

Subgenus 1. Plegmosphærantha, Haeckel.

Definition.—Inside and outside of the spongy shell-wall smooth, closed by a lattice-plate with polygonal meshes.

1. Plegmosphæra maxima, n. sp.

Radius of the spherical shell-cavity eight to ten times as great as the thickness of the thin spongy wall. Inside and outside of the wall smooth, closed by a lattice-plate with irregular polygonal meshes. Only three or four meshes in the thickness of the wall.

Dimensions.—Diameter of the spongy sphere 0.8 to 1.0 mm., of its inner cavity 0.7 to 0.8, meshes 0.01 to 0.02, bars 0.002 to 0.003, central capsule 0.5 to 0.6, nucleus 0.1 to 0.15.

Habitat.—Central Pacific, Station 271, surface.

2. Plegmosphæra coelopila, n. sp.

Radius of the spherical shell-cavity eight to ten times as great as the thickness of the spongy wall. Inside and outside of the wall closed by a smooth lattice-plate with irregular polygonal meshes, five to ten times as broad as the bars.

Dimensions.—Diameter of the shell 0.32, of its cavity 0.26, meshes 0.01 to 0.02, bars 0.002.

Habitat.—North Atlantic, Færöe Channel, Gulf Stream, John Murray.

3. Plegmosphæra pachypila, n. sp.

Radius of the spherical shell-cavity about equal to the thickness of the spongy wall. Inside and outside of the wall closed by a smooth lattice-plate with irregular polygonal meshes, three to six times as broad as the bars.

Dimensions.—Diameter of the shell 0.24, of its cavity 0.12.

Habitat.—North Pacific, Station 250, surface.

Subgenus 2. Plegmosphærella, Haeckel.

Definition.—Inside of the spongy shell-wall closed by a smooth lattice-plate, outside rough, spongy, with prominent thorns.

4. Plegmosphæra entodictyon, n. sp.

Radius of the spherical shell-cavity half as great as the thickness of the spongy wall. Inside of the wall closed by a smooth lattice-plate, outside rough, spongy.

Dimensions.—Diameter of the shell 0.24, of its cavity 0.08.

Habitat.—South Pacific, Station 300, surface.

5. Plegmosphæra leptodictyon, n. sp.

Radius of the spongy shell-cavity six times as great as the thickness of the spongy wall. Inside of the wall closed by a smooth lattice-plate, outside rough spongy.

Dimensions.—Diameter of the shell 0.44, of its cavity 0.36.

Habitat.—Central Pacific, Station 266, surface.

Subgenus 3. Plegmosphæromma, Haeckel.

Definition.—Inside of the spongy shell-wall rough spongy, without lattice-plate, outside closed by a smooth lattice-plate.

6. Plegmosphæra exodictyon, n. sp. (Pl. 18, fig. 8).

Radius of the spongy shell-cavity only one-fourth as great as the thickness of the spongy shell-wall. Outside of the wall closed by a smooth lattice-plate, inside rough, spongy.

Dimensions.—Diameter of the shell 0.4, of its cavity 0.08.

Habitat.—South Atlantic, Station 325, surface.

Subgenus 4. Plegmosphærusa, Haeckel.

Definition.—Inside and outside of the spongy shell-wall rough, with spongy or spiny surface, without lattice-plate.

7. Plegmosphæra leptoplegma, n. sp.

Radius of the spherical shell-cavity half as great as the thickness of the loose spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes ten to twenty times as broad as the bars.

Dimensions.—Diameter of the shell 0.3, of its cavity 0.088.

Habitat.—North Atlantic, Station 253, surface.

8. Plegmosphæra pachyplegma, n. sp.

Radius of the spherical shell-cavity about equal to the thickness of the dark and dense spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes three to five times as broad as the bars.

Dimensions.—Diameter of the shell 0.2, of its cavity 0.1.

Habitat.—Central Pacific, Station 270, surface.

Genus 27. Spongoplegma,^[19] Haeckel, 1881, Prodromus, p. 455.

Definition.—Liosphærida forming a sphere of spongy framework, which encloses in the centre one single latticed medullary shell.

The genus Spongoplegma may be regarded as a Carposphæra, in which the simple latticed cortical shell is represented by an irregular spongy framework, immediately enclosing the simple latticed medullary shell.

1. Spongoplegma antarcticum, n. sp.

Cortical shell with loose spongy framework and rough surface, four to six times as broad as the enclosed simple medullary shell. Pores of the latter regular circular, twice as broad as the bars. From its surface arise numerous (forty to fifty or more) short radial beams, which become forked and compose, by communication of lateral branches, the spongy cortical shell.

Dimensions.—Diameter of the spongy cortical shell 0.2 to 0.3 of the latticed medullary shell 0.05 to 0.06.

Habitat.—Antarctic Ocean, in large number, together with Cromyosphæra antarctica; in the Diatom ooze of Station 157 (depth 1950 fathoms).

Genus 28. Spongodictyon,^[20] Haeckel, 1862, Monogr. d. Radiol., p. 459.

Definition.—Liosphærida forming a sphere of spongy framework, which encloses in the centre a double latticed concentric medullary shell.

The genus Spongodictyon can be regarded as a Thecosphæra, in which the simple latticed cortical shell is represented by an irregular spongy framework, which immediately encloses the double latticed medullary shell. Sometimes this latter appears triple, the inner surface of the spongy cortical shell forming a smooth spherical lattice-plate, separated by an interval from the double medullary shell.

Subgenus 1. Dictyoplegma, Haeckel, 1862, Monogr. d. Radiol, p. 458.

Definition.—Spongy cortical shell enveloping immediately the double medullary shell.

1. Spongodictyon spongiosum, Haeckel.

Dictyosoma spongiosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 31, Taf. ii. figs. 9-11. Dictyoplegma spongiosum, Haeckel, 1862, Monogr. d. Radiol., p. 458.

Spongy framework of the cortical shell loose, with large, polygonal roundish meshes, on an average as large as the double medullary shell, which is immediately enveloped by it. Both concentric medullary shells with subregular roundish pores, twice as broad as the bars.

Dimensions.—Diameter of the cortical shell 0.2 to 0.3 or more; of the outer medullary shell 0.03, inner 0.01.

Habitat.—Mediterranean (French south coast, surface), J. Müller.

2. Spongodictyon cavernosum, n. sp.

Spongy framework of the cortical shell rather compact in the inner part, which immediately envelops the double medullary shell; very loose, with large caverns in the outer part, caverns of the surface larger than the medullary shell. Both medullary shells with regular circular pores, three times as broad as the bars.

Dimensions.—Diameter of the cortical shell 0.3 to 0.4, outer medullary shell 0.1, inner 0.03.

Habitat.—Tropical Atlantic, Station 338, surface.

Subgenus 2. Spongodictyoma, Haeckel.

Definition.—Spongy cortical shell on the inner surface with a smooth lattice-plate (or third medullary shell), which is connected by radial beams with the inner double medullary shell.

3. Spongodictyon trigonizon, Haeckel.

Spongodictyon trigonizon, Haeckel, 1862, Monogr. d. Radiol., p. 459, Taf. xxvi. figs. 4-6. Dictyosoma trigonizon, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 841.

Spongy framework of the cortical shell very loose, with very large, for the most part triangular meshes, which are two to six times as large as the enclosed double medullary shell. From the surface of the latter arise numerous radial beams, which are connected by a spherical lattice-plate, forming the smooth inner surface of the spongy sphere (or a third medullary shell). The structure of the framework reminds one of the Phæodarium Sagena (Pl. 108). Pores of both medullary shells regular circular, twice as broad as the bars.

Dimensions.—Diameter of the cortical shell 0.5 to 1.15, outer medullary 0.05, inner 0.035.

Habitat.—Mediterranean, Messina, surface.

4. Spongodictyon arcadophoron, n. sp.

Spongy framework of the cortical shell in the inner part very loose, in the outer part more compact; outer meshes scarcely as large as the inner medullary shell (or only half as large), inner meshes two to four times as large. From the surface of the double medullary shell arise numerous radial beams, which are forked at equal distances from the centre; the fork branches are curved and united together by dichotomous branches, like elegant arcades; and these arcades form together the large polygonal meshes on the inside of the cortical shell (or a third medullary shell). Both medullary shells with regular circular pores, of the same breadth as the bars.

Dimensions.—Diameter of the cortical shell 0.2, outer medullary shell 0.04, inner 0.02.

Habitat.—Tropical Atlantic, Station 349, surface.

Family VI. Collosphærida, J. Müller^[21] (Pls. 5-8).

Definition.—Sphæroidea living associated in colonies, united by an alveolar jelly-body, and connected by the network of anastomosing pseudopodia.

The family Collosphærida comprises all polyzous or social Sphæroidea, and constitutes the only polyzoic group among the Sphærellaria. This group was first constituted by J. Müller as "Radiolaria polyzoa with shells."^[22] Formerly following his authority, in my Monograph I had separated them from the other Sphæroidea and united them with the social Collodaria (Sphærozoida).^[23] Also R. Hertwig in his Organismus der Radiolarien^[24] united them with his Sphærozoea. In my Prodromus^[25] I had retained this isolated position. But a further careful study has convinced me that this isolation is not truly natural, and that the Collosphærida are only "social Ethmosphærida" which have arisen from this solitary subfamily by adaptation to colonial life. There are some forms of Collosphærida which are nearly identical with some forms of Ethmosphærida, only differing from the latter by their association in colonies; and in some forms of both groups it is quite impossible to decide whether the isolated shells appertain to one or to the other family.

The isolated shell of the Collosphærida is almost constantly (with few exceptions) a simple extracapsular lattice-shell, as in the Monosphærida; only the small group of Clathrosphærida (with the genera Clathrosphæra and Xanthiosphæra) exhibit an exception, the simple lattice-shell being overgrown by an external mantle or veil of very thin, cobweb-like, irregular lattice-work (Pl. 8, figs. 6-11). Therefore these Clathrosphærida bear to the Acrosphærida (or the common simple Collosphærida) a relation similar to that which Liosphæra (p. 76) bears to Cenosphæra; both shells are extracapsular "cortical shells" at a very short distance apart. In the Collosphærida true concentric medullary shells never occur; the central capsule always lies quite freely in the simple or double cortical shell, separated from it by a jelly-veil.

Although a well marked difference in the simple lattice-shell of the social Collosphærida and the solitary Ethmosphærida does not exist, nevertheless in most cases the two shells can be distinguished by a practiced observer. The simple fenestrated shells of the monozoic Ethmosphærida are commonly quite regular spheres in a mathematical sense, or regular "endospherical polyhedra"; whereas in the Collosphærida they are commonly more or less irregular, often to an extraordinary degree (Pls. 5-8). Some species of Collosphærida, however, also possess quite regular spherical shells. Another difference is often shown in the lattice-work of the shells, which in the Collosphærida is nearly always very irregular, and exhibits a peculiar tendency to the production of radial, conical, or cylindrical tubules. These occur as well on the inside as on the outside of the shell, and the tubules are now more conical, now more cylindrical; their wall either solid or pierced by pores (Pls. 5-8). The tubules are commonly very irregular in form, size, and disposition; distinguished, however, by a number of hereditary peculiarities, which are sufficient for the distinction of genera. Similar tubules occur also in some genera of solitary Ethmosphærida (Coscinomma, Ethmosphæra, Conosphæra, &c., Pl. 12); but the tubules are here much more regular and not so highly developed.

Besides the tubules of the fenestrated shells, in some genera of Collosphærida the surface is armed with irregular thorns, rarely with more regular radial spines. But these spines obtain constantly the character of accessory by-spines, and remain short and thin. In this family typical radial spines never occur in a regular and characteristic disposition, corresponding to dimensive axes, as is the case in nearly all solitary Sphæroidea, only excepting the Liosphærida. Commonly these spines or thorns serve as protective arms for the shell-meshes, surrounding them often in the form of coronels. Often the lattice-plate of the irregular roundish shell is tubercular, elevated into irregular protuberances, bearing on the top a short spine or thorn (Pl. 8).

The Central Capsule of the Collosphærida is always a regular sphere, as in all other Sphæroidea; it is constantly placed within the lattice-shell, and commonly much smaller than it, separated from it by a thick jelly-veil. A remarkable difference from the solitary Sphæroidea is shown in the early division of the nucleus. Commonly the central capsule of the Collosphærida contains in its centre a large oil-globule, surrounded by very numerous small nuclei. R. Hertwig estimated this difference as so important, that he separated the social "Sphærozoea" and the solitary "Peripylea" as two different orders. As already shown above (p. 7, 24), we cannot support this separation, and are now convinced that this difference in the development of the spores—just as in the Collodaria—is the consequence of an adaptation to social life.

The common jelly-body, in which the numerous central capsules and their enveloping shells are united, exhibits in the Collosphærida quite the same characters as in the other social Radiolaria, the Collozoida and Sphærozoida. The jelly-body is very voluminous, commonly spherical, often cylindrical, of considerable size; constantly containing numerous large alveoles. Often each shell is enclosed in a separate alveole with rather solid wall (Pl. 6, fig. 2). Sometimes in the dead colonies all shells are united in the central part of the jelly-body, whilst its peripheral part is composed of a stratum of large alveoles (Pl. 8, fig. 11); at other times no alveoles are visible (Pl. 7, fig. 11). In many living colonies I found a very large spherical alveole with thick wall in the centre of the spherical colony, surrounded by many strata of delicate thin-walled alveoles (Pl. 5, fig. 1). In this case often the inner younger capsules were naked, without shells, the outer only surrounded by shells. Already in my Monograph I had described the same peculiar formation.^[26]

Synopsis of the Genera of Collosphærida.

I. Subfamily Acrosphærida. (Lattice-shell simple, without an external mantle of network.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Outside of the shell smooth, without spines or tubuli.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Inside without tubuli.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Inside smooth,	29. Collosphæra.
						Inside spiny,	30. Tribonosphæra.
				Inside with centripetal tubuli.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Tubuli imperforated,	31. Pharyngosphæra.
						Tubuli fenestrated,	32. Buccinosphæra.
		Outside of the shell armed with solid spines, but with hollow tubuli.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Spines irregularly scattered on the surface,	33. Acrosphæra.
						Each larger pore with one single spine,	34. Odontosphæra.
						Each larger pore with a coronal of spines,	35. Chœnicosphæra.
		Outside of the shell with irregular radial tubuli, the wall of which is solid, not fenestrated.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Tubuli simple, not branched.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Mouth of the tubuli truncated, smooth,	36. Siphonosphæra.
						Mouth with one single large tooth,	37. Mazosphæra.
						Mouth with a coronal of teeth,	38. Trypanosphæra.
				Tubuli irregularly branched, each with two to four or more openings,			39. Caminosphæra.
		Outside of the shell with irregular radial tubuli, open on both ends, with fenestrated wall.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Mouth of the tubuli truncated, smooth,	40. Solenosphæra.
						Mouth with one single large tooth,	41. Otosphæra.
						Mouth with a coronal of teeth,	42. Coronosphæra.
II. Subfamily Clathrosphærida. (Lattice-shell double, with an external mantle of network.)					$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Surface of the outer shell smooth,	43. Clathrosphæra.
						Surface of the outer shell thorny,	44. Xanthiosphæra.

Subfamily Acrosphærida, Haeckel, 1881, Prodromus, p. 471.

Definition.—Collosphærida with one simple lattice-shell around every central capsule of the cœnobium.

Genus 29. Collosphæra,^[27] J. Müller, 1855.

Definition.—Collosphærida with simple shells, smooth on the inside and on the outside, without any spines or tubuli.

The genus Collosphæra is the most simple form of all Collosphærida, and must be regarded as the common ancestral form of this family. As the lattice-shell is quite a simple sphere, without any spines, tubules, or other peculiar productions, it agrees perfectly with Cenosphæra, and represents the social or polyzoid aggregate of this solitary or monozoid genus. Therefore a certain distinction between the isolated shells of the two genera is often very difficult or even impossible; but commonly this distinction is possible owing to the circumstance, that in the majority of the Collosphæræ the shell is more or less irregular roundish or polyhedral, not quite spherical, as in Cenosphæra. Dermatosphæra, Ehrenberg, is a Collosphæra with small pores (compare L. N. 16, p. 533).

Subgenus 1. Eucollosphæra, Haeckel.

Definition.—Shell a regular or subregular sphere.

1. Collosphæra primordialis, n. sp.

Shell a regular sphere, with very delicate and regular network of hexagonal meshes. Six to eight meshes in the half meridian of the shell. Diameter of the meshes ten to fifteen times as broad as the thin bars between them. Can be regarded as social form of Cenosphæra primordialis.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.008.

Habitat.—Central Pacific, Stations 271 to 274, surface.

2. Collosphæra regularis, n. sp.

Shell a regular sphere, with a perfectly regular network of circular meshes, all of the same size. Ten to twelve meshes in the half meridian of the shell. Diameter of the meshes the same as that of the bars between them.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.005 to 0.006.

Habitat.—Indian Ocean, Madagascar, surface, Rabbe.

3. Collosphæra globularis, n. sp.

Shell a regular sphere, with subregular network of circular meshes of different sizes; few large pores between many smaller pores. Ten to twenty meshes in the half meridian of the shell. Diameter of the meshes from half to twice as broad as that of the bars.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.008, breadth of the bars 0.004 to 0.008.

Habitat.—Tropical and subtropical zone of both hemispheres, widely distributed; Canaries, Azores, Cape Verde Islands, Guinea Coast, Brazil Coast, Indian Ocean, Madagascar, Ceylon, surface.

Subgenus 2. Dyscollosphæra, Haeckel.

Definition.—Shell not a regular sphere, but irregular roundish, in all degrees of variation between subspherical and polyhedral or quite irregular forms.

4. Collosphæra huxleyi, J. Müller.

Collosphæra huxleyi, J. Müller, 1855, Abhandl. d. k. Akad. d. Wiss. Berlin, pp. 55-59, Taf. viii. figs. 6-9.

Collosphæra huxleyi, Haeckel, 1862, Monogr. d. Radiol., p. 534, Taf. xxxiv.

Collosphæra huxleyi, Cienkowski, 1871, Archiv f. mikrosk. Anat., Bd. vii. p. 374, Taf. xxix. figs. 1-6.

Collosphæra ligurina, J. Müller, 1856, Monatsber. d. k. Akad. d. Wiss. Berlin, p. 481.

Thalassicolla punctata, var., Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 434, pl. xvi. fig. 6.

Shell subspherical, somewhat irregular, sometimes with more or less superficial impressions, with irregular network of roundish meshes. Eight to sixteen meshes in the half meridian of the shell, one to three times as broad as their bars. Very variable, with direct transition-forms to other species of this genus, especially to Collosphæra globularis, Collosphæra tuberosa, Collosphæra pyriformis, and Collosphæra polyedra.

Dimensions.—Diameter of the shell 0.1 to 0.16, of the pores 0.004 to 0.012, of the bridges 0.003 to 0.006.

Habitat.—Cosmopolitan; common in the greater part of the warmer seas, surface.

5. Collosphæra polygona, n. sp. (Pl. 5, fig. 13).

Collosphæra huxleyi var., Haeckel, 1862, Monogr. d. Radiol., Taf. xxxiv. fig. 5.

Shell irregular polygonal, with very delicate, irregular network of polygonal meshes, four to twelve times as broad as the bars. Ten to twenty pores on the half meridian of the shell.

Dimensions.—Diameter of the shell 0.1 to 0.2, of the pores 0.012 to 0.004, of the bars 0.001 to 0.002.

Habitat.—Mediterranean, Atlantic, surface; Stations 348 to 354.

6. Collosphæra pyriformis, Haeckel, n. sp.

Shell irregular, rounded, ovate or pear-shaped, with irregular network of rounded or nearly polygonal meshes. Ten to twenty meshes in the half meridian of the shell, one to three times as broad as the bars. Commonly one large opening (two to three times as broad as the largest meshes) on the thinner end of the ovate shell (corresponding to the insertion of a pear-stalk); sometimes two or three such large openings.

Dimensions.—Diameter of the shell 0.1 to 0.15, of the pores 0.008 to 0.016, of the bridges 0.004 to 0.008.

Habitat.—Tropical zone—Cape Verde Islands, Ceylon; Central Pacific, Stations 266 to 272, 348 to 352, &c.

7. Collosphæra polyedra, n. sp.

Trisolenia zanguebarica, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 301, Taf. x. fig. 11.

Shell irregular, polyhedral, with even or somewhat vaulted sides, and obtuse ridges between them. Network more or less irregular, with small rounded meshes, quite as broad or twice as broad as their bars. Besides these small pores constantly some large round openings (commonly three to six), situated on the corners of the polyhedral shell, four to six times as large as the pores. Often an acute tooth on the edge of each large opening. Transition-form between Collosphæra and Solenosphæra or Odontosphæra.

Dimensions.—Diameter of the shell 0.1 to 0.15, of the pores 0.004 to 0.008, of their bridges 0.004, of the large openings 0.24 to 0.032.

Habitat.—Tropical zone of the Pacific and the Indian Ocean; Stations 266 to 272, surface.

8. Collosphæra tuberosa, n. sp.

Collosphæra huxleyi, var., Haeckel, 1862, Monogr. d. Radiol., Taf. xxxiv. figs. 3, 9.

Shell very irregular, between subspherical and polyhedral in form, but always with irregular impressions, boils or bosses, and between these different rounded prominent tubercles and ridges. Network irregular, strong, with rounded, subcircular or nearly polygonal meshes. Ten to thirty pores in the half meridian of the shell. Diameter of the meshes half to four times as broad as that of the thick bars.

Dimensions.—Diameter of the shell very variable in the same cœnobium, 0.05 to 0.2, of the pores 0.002 to 0.008, breadth of the bridges 0.004 to 0.006.

Habitat.—Cosmopolitan, common in all warmer seas, surface.

9. Collosphæra irregularis, n. sp.

Collosphæra huxleyi, var., Haeckel, 1862, Monogr. d. Radiol., Taf. xxxiv. fig. 8.

Shell quite irregular, knotty or bulbous, with irregular impressions, and prominent knobs or bulbs between them. Network thin, fragile, quite irregular, with polygonal meshes of most unequal size and form. Five to twenty pores in the half meridian of the shell. Diameter of the meshes two to ten times as broad as that of the thin bars.

Dimensions.—Diameter of the shell very variable in the same cœnobium, 0.04 to 0.24, of the pores 0.005 to 0.05, of the bridges 0.002 to 0.004.

Habitat.—Mediterranean, Atlantic, not common; Stations 348, 352, &c., surface.

Genus 30. Tribonosphæra,^[28] Haeckel, 1881, Prodromus, p. 471.

Definition.—Collosphærida with simple shells, on the inside with radial centripetal beams.

The genus Tribonosphæra differs from Collosphæra by a very peculiar and rare character, the development of centripetal radial sticks on the internal face of the shell; these beams are not united in the centrum, but finish freely in a certain distance from it.

1. Tribonosphæra centripetalis, n. sp. (Pl. 5, fig. 12).

Shell roundish or subspherical, with numerous small circular or roundish pores, about twice as broad as the bars. Twenty to thirty pores on the half meridian of the shell. Outside of the shell smooth, inside a variable number (ten to twenty) of thin, radial, centripetal sticks or spines, one-third or one-half as long as the radius of the shell. (In the central capsule many very large crystals, resting after the destruction of the capsule.)

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.003 to 0.005, of the bridges 0.001 to 0.002; length of the inner centripetal sticks 0.02 to 0.03.

Habitat.—Central Pacific, Station 271, surface.

Genus 31. Pharyngosphæra,^[29] n. gen.

Definition.—Collosphærida with simple shells, having on the inside radial centripetal tubes, the walls of which are solid.

The genus Pharyngosphæra differs from Collosphæra by the development of radial tubules on the inside of the shell, which are directed centripetally towards its centre. The wall of the tubule is solid, not latticed as in the following genus.

1. Pharyngosphæra stomodæa, n. sp. (Pl. 5, fig. 10).

Shell irregular polyhedral, with ten to fifteen polygonal faces and rounded edges. Pores very small, circular, irregularly scattered, smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. On the inside of every shell-face one short, nearly cylindrical, centripetal tubule, twice as long as broad, and about one-third as long as the shell radius. Outer umbilical mouth of the tubules somewhat wider than the inner truncated mouth.

Dimensions.—Diameter of the shell 0.11 to 0.12, of the pores 0.003 to 0.005, of the bars 0.01 to 0.02; length of the inner tubuli 0.02, breadth of them 0.01.

Habitat.—South Pacific, Station 288, depth 2600 fathoms.

Genus 32. Buccinosphæra,^[30] n. gen.

Definition.—Collosphærida with simple shells, having on the inside radial centripetal tubes, the walls of which are fenestrated.

The genus Buccinosphæra exhibits, on the inner surface of the shell, radial centripetal tubules similar to those of the foregoing Pharyngosphæra; but the walls of these tubes are here latticed, not solid; they represent therefore true invaginations of the whole shell-wall.

1. Buccinosphæra invaginata, n. sp. (Pl. 5, fig. 11).

Shell irregular roundish or nearly polyhedral, with a variable number of umbilical depressions, which are prolonged on the inside into cylindrical or somewhat conical, centripetal, fenestrated tubes, about one-third as long as the shell radius. Inner mouth of the tubes narrower, scarcely half as broad as the outer mouth, about equal to one-fourth the shell radius, truncated. Pores of the tubes and of the shell small, roundish, irregular in size and distribution, about as broad as the bars. Twenty-five to thirty pores in the half meridian of the shell. In all observed specimens the spherical central capsule (half as broad as the shell) contained a large number of crystals.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.001 to 0.003, of the bars 0.002 to 0.003; length of the tubuli 0.02; outer mouth 0.026, inner mouth 0.013; crystals in the central capsule 0.002 to 0.004, sometimes 0.008.

Habitat.—Philippine Islands (Samboangan), Station 213, surface.

2. Buccinosphæra tubaria, n. sp.

Shell irregular polyhedral with rounded edges, with a variable number of umbilical depressions, which are prolonged on the inside into large, nearly cylindrical, centripetal, fenestrated tubes, half as long as the shell radius. In the middle the tubes are somewhat constricted and narrower. Inner mouth of the tubes dilated, nearly as broad as the outer mouth, about equal to one-half the shell-radius, truncated. Pores of the tubes and of the shell large, roundish polygonal, irregular in size and distribution, three to four times as broad as the bars. Fifteen to twenty pores in the half meridian of the shell.

Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.008 to 0.012, of the bars 0.002 to 0.004; length of the tubuli 0.03; outer mouth 0.04, inner mouth 0.03.

Habitat.—North coast of New Guinea, Station 217, surface.

Genus 33. Acrosphæra,^[31] Haeckel, 1881, Prodromus, p. 471.

Definition.—Collosphærida with simple shells, the outer surface of which is covered with radial, irregularly scattered spines.

The genus Acrosphæra differs from its ancestral genus Collosphæra by the development of spines on the outer surface of the shell. These are either short, straight, radial spines, or oblique and often curved; their base is often inflated; they are irregularly scattered on the whole surface between the pores.

1. Acrosphæra erinacea, n. sp.

Shell a regular sphere, everywhere covered with small, very numerous, straight radial spines, regularly scattered between the pores. In the half meridian of the shell ten to twelve circular pores, all of the same form and size, double as broad as the bars. Spines bristle-shaped, very thin, solid, about as long as the diameter of the pores.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.008 to 0.012; length of the spines 0.01.

Habitat.—Tropical zone of the Atlantic, coast of Brazil, Rabbe, surface.

2. Acrosphæra echinoides, n. sp. (Pl 8, fig. 1).

Shell a regular sphere, covered with numerous, straight, radial spines, irregularly scattered over the whole surface. In the half meridian of the shell twenty to thirty irregular roundish pores of variable size, one to four times as broad as the bars. Spines conical, strong, quite radial, at the top of small conical elevations, which are perforated by from three to six pores.

Dimensions.—Diameter of the shell 0.12 to 0.15, of the pores 0.002 to 0.008; length of the spines 0.015, of their basal zones 0.01.

Habitat.—South-east corner of the Pacific, Valparaiso, Station 298, surface.

3. Acrosphæra setosa, Haeckel.

Polysolenia setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 10.

Shell a regular sphere, covered with numerous bristle-shaped radial spines, irregularly scattered between the pores. In the half meridian of the shell two to four very large circular pores (equal to one-third the radius), and between them numerous very small, point-like pores.

Dimensions.—Diameter of the shell 0.05 to 0.08, of the large pores 0.01, of the small 0.001; length of the spines 0.01 to 0.02.

Habitat.—West Tropical Pacific, Philippine Sea, Station 206, depth 2100 fathoms.

4. Acrosphæra spinosa, Haeckel.

Collosphæra spinosa, Haeckel, 1862, Monogr. d. Radiol., p. 536, Taf. xxxiv. figs. 12, 13. Collosphæra spinosa, Cienkowsky, 1871, Archiv f. mikrosk. Anat., vii. p. 374, Taf. xxix. figs. 7-17.

Shell a regular or subregular sphere, covered with numerous, obliquely standing spines, irregularly scattered over the surface. In the half meridian of the shell fifteen to twenty irregular roundish pores of very different form and size, one to four times as broad as their bars. Spines conical, irregularly diverging and curved, their hollow base perforated by several pores, not longer than the diameter of the largest pores.

Dimensions.—Diameter of the shell 0.1 to 0.2, of the pores 0.001 to 0.04; length of the spines 0.01 to 0.02.

Habitat.—Mediterranean, Messina; Canary Islands, Haeckel.

5. Acrosphæra collina, n. sp. (Pl. 8, fig. 2).

Shell quite irregular, polyhedrical, hilly, with a variable number (eight to sixteen) of large conical hill-like prominences; every cone or hill about as high as broad, perforated by the same pores as the shell, on its top bearing a larger irregular roundish pore, and on its edge one single bristle-like spine, not larger than the diameter of this pore, obliquely inserted. In the half meridian of the shell twenty to thirty irregular roundish pores of very different size, one to six times as broad as the bars. A very characteristic species, closely resembling the following Odontosphæra.

Dimensions.—Diameter of the shell 0.15 to 0.25, of the pores 0.005 to 0.02; length of the spines 0.01 to 0.02, height of the hills from which they rise 0.03 to 0.04.

Habitat.—North coast of New Guinea, Station 218, surface.

6. Acrosphæra inflata, n. sp. (Pl. 5, fig. 7).

Mazosphæra inflata, Haeckel, 1879, Atlas, loc. cit.

Shell more or less irregular, polyhedral, hilly, with a variable number (six to twelve) of large pyramidal, hill-like prominences; every hill about as high as broad, on the top a strong conical, radial, or obliquely inserted spine, inflated, with three to six very large polygonal meshes, much larger than the other pores between the hills, which are also polygonal, two to six times as broad as the bars. Ten to fifteen pores on the half meridian.

Dimensions.—Diameter of the shell 0.1 to 0.14, of the largest pores 0.05, of the smallest 0.005; length of the spines 0.02 to 0.03.

Habitat.—North Atlantic, Station 64, surface.

Genus 34. Odontosphæra,^[32] n. gen.

Definition.—Collosphærida with simple shells, the outside of which bears single scattered spines, one single spine on the margin of each larger pore.

The genus Odontosphæra is distinguished from the foregoing Acrosphæra by the peculiar disposition of the spines, which are not scattered on the outside of the shell between the pores, but so disposed that each larger pore is protected by one single spine, obliquely placed over it.

1. Odontosphæra monodon, n. sp. (Pl. 5, fig. 5).

Shell spherical or subspherical, with very small and numerous circular pores, much smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. Between them a variable number of larger roundish apertures (mostly twelve to sixteen) irregularly scattered, one-fourth to one-fifth as broad as the shell radius. On the margin of every larger aperture a single (rarely two or three) sharp conical tooth, about as long as the diameter of the aperture, and obliquely laid over them.

Dimensions.—Diameter of the shell 0.1 to 0.13, of the pores 0.001 to 0.003, of the bars 0.01 to 0.02, of the larger apertures 0.01 to 0.02.

Habitat.—Sunda Archipelago, Station 192, surface.

2. Odontosphæra cyrtodon, n. sp. (Pl. 5, fig. 6).

Shell spherical or subspherical, with numerous roundish pores of very irregular size and distribution, mostly larger than the bars. Ten to twelve pores on the half meridian of the shell. Between them a variable number (mostly six to nine) of large roundish pores, about half as broad as the shell radius, armed on one side of the margin with one single large tooth, about as long as the diameter of the aperture, hook-like, curved, and obliquely laid over them.

Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.01 to 0.02, of the bars 0.003 to 0.006, of the larger apertures 0.03 to 0.04.

Habitat.—Indian Ocean, near the Cocos Islands, Rabbe, surface.

Genus 35. Chœnicosphæra,^[33] n. gen.

Definition.—Collosphærida with simple shells, armed on the outside with radial spines, forming elegant coronals around the larger pores.

The genus Chœnicosphæra is characterised by the peculiar disposition of its radial spines, which form protective coronals around the larger pores, or even around all pores of the shell.

Subgenus 1. Chœnicosphærula.

Definition.—A coronal of spines around every pore of the shell.

1. Chœnicosphæra murrayana, n. sp. (Pl. 8, fig. 4).

Shell spherical, with large circular or roundish pores of unequal size, two to four times as broad as the bars. Ten to twelve pores in the half meridian of the shell. Margin of every pore with a coronal of six to nine short and acute spines, not longer than the half diameter of the pore. No spines between the pores.

Dimensions.—Diameter of the shell 0.16 to 0.2, of the pores 0.02 to 0.03; length of the spines 0.008 to 0.012.

Habitat.—Færöe Channel (Gulf Stream), common. Expedition of H.M.S. "Triton," John Murray.

2. Chœnicosphæra flosculenta, n. sp.

Shell spherical, with large circular or roundish pores of different size, three to six times as broad as the bars. Six to eight pores in the half meridian of the shell. Margin of every pore somewhat prominent, with a coronal of ten to twenty parallel acute spines of different length, the largest somewhat longer than the diameter of the pore. No spines between the pores.

Dimensions.—Diameter of the shell 0.12 to 0.15, of the pores 0.02 to 0.04; length of the spines 0.02 to 0.05.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subgenus 2. Chœnicosphærium.

Definition.—A coronal of spines only around the larger pores, not around the smaller.

3. Chœnicosphæra nassiterna, n. sp. (Pl. 8, fig. 3).

Shell spherical, with circular or roundish pores of very different size. The smaller pores very numerous, without coronal of spines, roundish, about as broad as the bridges. Twenty to thirty pores in the half meridian of the shell. Between them, irregularly scattered, a small number (eight to twelve) of very large circular pores, one-third to one-half as broad as the radius of the shell, armed with a coronal of six to nine parallel, straight, acute spines, about half as long as the radius of the shell.

Dimensions.—Diameter of the shell 0.1 to 0.13, of the smaller pores 0.002 to 0.004, of the larger armed pores 0.02 to 0.03; length of the spines 0.03 to 0.04.

Habitat.—Philippine Islands, Mindanao, Station 213, depth 2050 fathoms.

4. Chœnicosphæra flammabunda, n. sp. (Pl. 8, fig. 5).

Shell spherical, with circular or roundish pores of very different size. The smaller pores very numerous and unequal, very irregularly scattered, hardly one-fourth to one-half as broad as the bridges between them. Twelve to twenty-four pores in the half meridian of the shell. Between them, irregularly scattered, a variable number (ten to twenty) of very large circular pores, about one-fourth as broad as the radius of the shell. The margin of these large pores is armed with a very irregular coronal of four to twelve unequal, curved acute spines, partly simple, partly branched like a deer-horn, one-fourth to one-half as long as the radius of the shell. Some other small spines irregularly scattered over the shell.

Dimensions.—Diameter of the shell 0.12 to 0.16, of the smaller pores 0.001 to 0.004, of the larger armed pores 0.016 to 0.024; length of the spines 0.02 to 0.04.

Habitat.—Central area of the Tropical Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

Genus 36. Siphonosphæra,^[34] J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss.

Berlin, p. 59.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external simple radial tubuli with solid wall; outer mouth of the tubuli truncated, smooth.

The genus Siphonosphæra is, next to Collosphæra, the most common of all Collosphærida, and rich in different species; all agreeing in the tubular prolongation of the pores, and corresponding therefore to Ethmosphæra among the simple Liosphærida.

Subgenus 1. Holosiphonia, Haeckel.

Definition.—All the pores or apertures of the shell prolonged into tubules.

1. Siphonosphæra pansiphonia, n. sp.

Shell a regular sphere, everywhere occupied by short, regular cylindrical tubes, all of the same size and form. Length of the tubules equal to their breadth and to the intervals between them. Ten to twelve tubules in the half meridian of the shell. This most regular species is nearly allied to Collosphæra regularis, and may be derived from it by tubular prolongation of all the regular pores.

Dimensions.—Diameter of the shell 0.1 to 0.12, length and breadth of the tubules 0.005 to 0.006.

Habitat.—Indian Ocean, Sunda Strait, Rabbe, surface.

2. Siphonosphæra marginata, n. sp.

Shell a regular or subregular sphere, occupied by numerous short cylindrical tubules of different sizes. Six to eight tubules in the half meridian of the shell. Diameter of the tubules about equal to their distance apart, but two to four times as large as their length.

Dimensions.—Diameter of the shell 0.1 to 14; length of the tubules 0.004 to 0.006, breadth of the tubules and the intervals 0.01 to 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Siphonosphæra tubulosa, J. Müller (Pl. 6, fig. 4).

Siphonosphæra tubulosa, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 59.

Siphonosphæra tubulosa, Haeckel, 1862, Monogr. d. Radiol., p. 532.

Collosphæra tubulosa, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 59.

Thalassicolla punctata, var., Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 435, pl. xvi. fig. 5.

Shell subspherical or roundish, somewhat irregular, occupied by a small number (five to ten) of short cylindrical tubules, irregularly scattered at great distances; intervals between the tubules very large, two to four times as broad as the length of the tubules, which is equal to their breadth and about one-fifth or one-sixth of the shell diameter. Only two or three tubules in the half meridian of the shell.

Dimensions.—Diameter of the shell 0.12 to 0.15, length and breadth of the tubules 0.02 to 0.03.

Habitat.—Equatorial zone of the Pacific, Stations 225, 265, 268, surface.

4. Siphonosphæra cyathina, n. sp. (Pl. 6, fig. 10).

Shell a regular sphere, everywhere occupied by short cup-like tubules of somewhat different size. In the half meridian of the shell about ten to twelve tubules, nearly cylindrical, but constricted in the middle. Inner and outer aperture of the tubule of the same size; their diameter equal to their length and distance.

Dimensions.—Diameter of the shell 0.1 to 0.12, length and breadth of the tubules 0.005 to 0.01.

Habitat.—West coast of Tropical Africa, Stations 348 to 352, surface.

5. Siphonosphæra patinaria, n. sp. (Pl. 6, figs. 7, 8).

Shell a regular or subregular sphere, occupied by numerous broad cup-like tubules of very different sizes. In the half meridian of the shell about six to eight tubules, very flat, circular or subcircular, much constricted in the middle. Diameter of the inner aperture larger than that of the middle stricture, smaller than that of the outer aperture of the tubule; outer diameter two to four times as great as their length.

Dimensions.—Diameter of the shell 0.1 to 0.15, of the pores 0.01 to 0.04; length of the tubules 0.01, breadth 0.02 to 0.04.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

6. Siphonosphæra infundibulum, n. sp.

Shell subspherical or irregular rounded, occupied by a small number (six to twelve) of large funnel-like tubules of very different size, scattered irregularly at great distances. Intervals between the tubules larger than their length, which surpasses the radius of the shell. Outer opening of the funnels three to four times as broad as the inner.

Dimensions.—Diameter of the shell 0.15; length of the tubules 0.05 to 0.09.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

7. Siphonosphæra conifera, n. sp. (Pl. 6, fig. 9).

Shell subspherical, everywhere occupied by irregular conical tubules, the length of which nearly reaches the shell radius. Inner aperture of the cones two to three times as large as the outer. Four to five tubules in the half meridian of the shell. Distances between the bases of the cones small and irregular.

Dimensions.—Diameter of the shell 0.06 to 0.08, length of the tubules 0.03 to 0.04; inner aperture of the cones 0.01 to 0.02, outer aperture 0.008 to 0.01.

Habitat.—Indian Ocean, Cocos Islands, Rabbe, surface.

8. Siphonosphæra fragilis, n. sp.

Shell quite irregular roundish or nearly ovate, very thin and fragile, everywhere occupied by irregular, short, and broad cylindrical or conical tubes. Six to ten tubes in the half meridian of the shell. Diameter of the tubules about one-eighth that of the shell, three to four times as large as the length of the tubules, and the distance apart of their bases.

Dimensions.—Diameter of the shell 0.16 to 0.24, of the tubules 0.02 to 0.03; length of the tubules 0.006 to 0.008, distance of them 0.005 to 0.009.

Habitat.—East coast of Australia, Sydney, Faber; Station 165, surface.

Subgenus 2. Merosiphonia, Haeckel.

Definition.—Only part of the shell apertures prolonged in tubules, the others simple.

9. Siphonosphæra socialis, n. sp. (Pl. 6, figs. 1, 2).

Shell a regular or subregular sphere, bearing only a small number (one to four, commonly two to three) of short and broad cylindrical tubules, irregularly scattered. Between them many small circular or subcircular pores of different sizes, double as broad as their bars. Eight to ten pores in the half meridian of the shell. Tubules three to six times as broad as the pores, about as long as broad, now quite cylindrical, now somewhat dilated at the outer opening. (Although the shells and cells of this common species are among the smallest, their colonies are among the largest, often containing more than one hundred social individuals, often enclosed in alveoles.)

Dimensions.—Diameter of the shell 0.04 to 0.05, of the pores 0.002 to 0.004, of the tubules 0.015 to 0.02; length of them about the same.

Habitat.—Tropical and subtropical part of the Eastern Atlantic, Cape Verde Islands, Canaries, very common, Haeckel; Stations 338 to 353, surface.

10. Siphonosphæra polysiphonia, n. sp.

Shell a regular or subregular sphere, bearing twelve to sixteen circular pores in its half meridian. Nearly one half the pores simple, very small; the other half prolonged into short cylindrical tubules, half as long as broad, two to four times as broad as the pores and their intervals. This species is nearly related to the foregoing, which it represents in the western tropical part of the Atlantic, but differs constantly in the double size of the shell and the much larger number of the tubules.

Dimensions.—Diameter of the shell 0.06 to 0.09, of the pores 0.002 to 0.004, of the tubules 0.01 to 0.012; their length 0.006 to 0.008, surface.

Habitat.—Tropical and subtropical part of the Western Atlantic, coast of Brazil, &c., Rabbe.

11. Siphonosphæra macrosiphonia, n. sp.

Shell a regular sphere, with numerous very small pores of equal size and distribution. Twelve to sixteen pores in its half meridian. Bars (between the pores) three to four times as broad as their diameter. Only a small number (two to four) of very long cylindrical tubes, irregularly scattered, nearly as long or somewhat longer than the shell diameter; now quite straight, now somewhat curved. Diameter of the cylinders four to six times as large as that of the pores.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.004, of the tubules 0.015 to 0.018; length of the tubules 0.08 to 0.16.

Habitat.—Central Tropical Pacific, Station 266 to 272, surface.

12. Siphonosphæra serpula, n. sp. (Pl. 6, fig. 6).

Shell a regular sphere, with numerous very small pores of equal size and distribution. Eight to ten pores in its half meridian; bars between them three to four times as broad as their diameter. Only a small number (six to eight) of very long and snake-like, contorted, cylindrical tubes, irregularly scattered. The shape of the latter is very much like that of the calcareous tubes of some species of Serpula; they are nearly as long as, or longer than, the shell diameter, and four to six times as broad as the pores.

Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.003 to 0.005, of the tubules 0.02 to 0.022; length of the tubules 0.1 to 0.2.

Habitat.—North Eastern Pacific, Station 252 to 262, Sandwich Islands, Haltermann.

13. Siphonosphæra chonophora, n. sp. (Pl. 6, fig. 5).

Shell a regular or subregular sphere, with numerous very small pores of equal size and distribution, ten to twelve in its half meridian. Bars between the pores four to six times their diameter. Only a small number (two to six) of very large funnel-like tubules, irregularly scattered. The inner half of these tubules is a short cylindrical tube, of the same thickness as the shell, three to four times as broad as the pores; the outer half is an irregular funnel, suddenly expanded, with siliceous walls of the utmost tenuity and fragility, often irregularly folded and contorted, like a decayed flower-calyx, often half as large as the shell.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.003 to 0.005, inner half of the tubules 0.015 to 0.02, outer funnel-like half 0.05 to 0.08.

Habitat.—South Pacific, Stations 285 to 295, surface.

14. Siphonosphæra pipetta, n. sp. (Pl. 6, fig. 3).

Shell more or less irregularly roundish or subspherical, occupied in part by very small pores, in part by very large cylindrical tubules, inflated in the middle. Number, form, and size of the tubes very irregular; commonly there are five to ten, half as long or as long as the shell radius; their inner and outer aperture about half as broad as their inflated middle part; three to nine times as broad as the pores. A very irregular and variable species.

Dimensions.—Diameter of the shell 0.1 to 0.15, of the pores 0.001 to 0.005, of the tubules 0.015 to 0.03; length of the tubules 0.03 to 0.08.

Habitat.—North Pacific, Stations 242 to 253, surface.

Genus 37. Mazosphæra,^[35] Ehrenberg, 1860.

Mazosphæra, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 833.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external simple radial tubuli with solid wall; outer mouth of each tubulus armed with a single tooth.

The genus Mazosphæra is intermediate between Siphonosphæra and Odontosphæra, agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a single large protective tooth on the outer opening.

1. Mazosphæra hippotis, n. sp. (Pl. 5, fig. 8).

Shell spherical, with circular pores of irregular size and distribution, scarcely half as broad as the bars; fifteen to twenty on the half meridian of the shell. Between them, irregularly distributed, a variable number (ten to fifteen) of short cylindrical radial tubules, about twice as long as broad, and half as long as the shell radius. Mouth of the tubuli obliquely truncated, having on one side a strong acute tooth.

Dimensions.—Diameter of the shell 0.11 to 0.12, of the pores 0.002 to 0.004, of the bridges 0.006 to 0.009; length of the tubuli 0.03, breadth of them 0.01 to 0.015.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

2. Mazosphæra lagotis, n. sp. (Pl. 5, fig. 9).

Shell spherical, with circular pores of irregular size and distribution, about as broad as the bars; twelve to sixteen on the half meridian. Between them, irregularly distributed, a variable number (eight to twelve) of long, cylindrical, curved tubules, three to six times as long as broad, and about as long as the shell radius; their external mouth lateral, obliquely truncated, ovate, having on one side a strong conical tooth.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.01; length of the tubuli 0.05 to 0.07.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Mazosphæra lævis, Ehrenberg.

Mazosphæra lævis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. vii. fig. 7.

Shell spherical, with very small pores, scarcely one-fourth as broad as the bars. Fifteen to twenty pores on the half meridian of the shell. Between them, irregularly distributed, a variable number (fifteen to twenty) of short conical tubules, about as long as broad, only one-fifth to one-sixth as long as the shell radius. Mouth of the tubuli truncated, with an obtuse short tooth on one side.

Dimensions.—Diameter of the shell 0.08 to 0.09, of the pores 0.001 to 0.002, of the bridges 0.005 to 0.008; length of the tubuli 0.01 to 0.02, breadth of them the same.

Habitat.—Philippine Islands (depth 3300 fathoms), Ehrenberg; Station 206, depth 2100 fathoms; Station 225, depth 4575 fathoms.

4. Mazosphæra apicata, Ehrenberg.

Mazosphæra apicata, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 316.

Shell spherical, without small pores, only with a variable number (ten to twenty) of short conical tubules, twice as long as broad, and half as long as the shell radius. Mouths of the tubuli obliquely truncated, with a strong acute tooth on one side. (This species differs from the two preceding by the want of the small pores between the tubules.)

Dimensions.—Diameter of the shell 0.08 to 0.1, of the tubules 0.01.

Habitat.—Philippine Islands (depth 3300 fathoms), Ehrenberg; north coast of New Guinea, depth 2000 fathoms; Station 217.

Genus 38. Trypanosphæra,^[36] n. gen.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external simple radial tubuli with solid walls; outer mouth of each tubulus armed with a coronal of spines.

The genus Trypanosphæra is intermediate between Siphonosphæra and Chœnicosphæra agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a coronal of teeth on their outer opening.

Subgenus 1. Trypanosphærula, Haeckel.

Definition.—All pores of the shell prolonged into short coronated tubules.

1. Trypanosphæra trepanata, n. sp. (Pl. 5, fig. 4).

Shell regular spherical, with regular circular pores of nearly equal size, at unequal distances, one to four times as broad as the bars. Eight to ten pores on the half meridian. All the pores prolonged into short cylindrical tubuli about as long as broad, armed on the external mouth with an elegant coronal of twenty to thirty straight bristle-shaped, parallel teeth.

Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.015 to 0.02; length of the tubuli 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Trypanosphæra dentata, n. sp.

Shell regular spherical, with regular circular pores of equal size, but at very different distances. Only three to four pores on the half meridian. All the pores prolonged into irregular curved, cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve short conical teeth on the distal end.

Dimensions.—Diameter of the shell 0.08 to 0.09; length of the tubuli 0.04, breadth 0.02.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 2. Trypanosphærium, Haeckel.

Definition.—Only part of the shell-pores prolonged into coronated tubules.

3. Trypanosphæra coronata, n. sp. (Pl. 5, fig. 3).

Shell regular spherical, with irregular roundish pores of very different sizes. On the half meridian four to six large and twelve to sixteen very small pores. About half of the large pores prolonged into short cylindrical tubuli, the outer mouth of each being armed with an elegant coronal of ten to twenty thin irregular teeth.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the large pores 0.01 to 0.02, of the small pores 0.001; length of the tubuli 0.012.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Trypanosphæra terebrata, n. sp.

Shell irregular roundish, with unequal, small, roundish pores. Sixteen to twenty pores on the half meridian. Six to eight larger pores are prolonged into curved cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve strong conical straight teeth on the distal end.

Dimensions.—Diameter of the shell 0.15, of the pores 0.001 to 0.003; length of the tubuli 0.08, breadth 0.02.

Habitat.—West Tropical Pacific, Station 225, depth 4575 fathoms.

5. Trypanosphæra transformata, n. sp. (Pl. 5, figs. 1, 2).

Shell quite irregular, of very variable, roundish, or polyhedral form, with small irregular roundish pores, two to four times as broad as the bars. Ten to thirty on the half meridian. The different form of the shell depends upon the variable number of tubuli, which arise at irregular distances from the shell; commonly three to four, often also five to six, more rarely one or two. The tubuli are now more conical, now more cylindrical, about as long as the shell radius, at other times scarcely one-half or one-third as long, with a coronal of ten to twenty more or less curved teeth on the narrower distal mouth. All the different forms are to be found in one and the same colony, as shown in fig. 1. This cœnobium, which I observed living in Ceylon, exhibited the same peculiar formation as I figured in Collosphæra huxleyi in my Monograph 1862 (Taf. xxxiv. fig. 1). In the centre of the jelly-sphere lies a large globular alveole, surrounded by numerous small, young central capsules without shell; whilst in the surface lies one layer of older capsules, enclosed in shells. Some of the younger capsules exhibit self-division.

Dimensions.—Diameter of the shells 0.08 to 0.12, pores 0.002 to 0.006; length and breadth of the tubuli 0.03 to 0.05.

Habitat.—Indian Ocean, Belligemma, Ceylon, surface.

Genus 39. Caminosphæra,^[37] n. gen.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external branched radial tubuli with solid wall.

The genus Caminosphæra differs from Siphonosphæra (and from all other Collosphærida) in the ramification of the tubuli, which arise from the pores; the walls of the tubuli are solid, not fenestrated.

1. Caminosphæra furcata, n. sp.

Shell spherical or subspherical, with a variable number (four to eight) of short cylindrical tubes, irregularly scattered, about as long as the radius of the shell. Every tube forked, with two cylindrical branches of the same size as the simple basal part of the tube. Mouth of the branches truncated, not dilated. Pores of the shell between the tubes very small, all of the same size, half as broad as their bars. Fifteen to twenty pores in the half meridian of the shell.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.001 to 0.002; length of the tubules 0.05 to 0.06, breadth of them 0.012 to 0.015.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

2. Caminosphæra elongata, n. sp.

Shell spherical, with a large number (twelve to twenty) of long cylindrical tubes, irregularly formed and scattered, somewhat longer than the diameter of the shell. Every tube forked at the distal end, with two or three short irregular branches of unequal size and form; branches much shorter than the undivided basal part of the tube. Mouth of the branches narrowed, truncated. Pores of the shell between the tubes about half as broad, irregularly roundish or polygonal, two to three times as broad as their bars. Ten to twelve pores in the half meridian of the shell.

Dimensions.—Diameter of the shell 0.05 to 0.07, of the pores 0.006 to 0.009; length of the tubules 0.06 to 0.09, breadth of them 0.015 to 0.02.

Habitat.—Tropical Central Pacific, Station 271, depth 2425 fathoms.

3. Caminosphæra dichotoma, n. sp. (Pl. 7, fig. 2).

Shell spherical, with a variable number (ten to fifteen) of cylindrical tubes, irregularly scattered, about as long as the radius of the shell. Every tube furcated, with two cylindrical branches of the same size as the simple basal part of the tube. Mouth of the branches dilated, funnel-like, twice as broad as the tube; the edges irregularly dentated or lacerated. Pores between the tubes small, one-third to one-sixth as broad as these, half as broad as their bars. Ten to twelve pores in the half meridian of the shell.

Dimensions.—Diameter of the shell 0.12 to 0.14, of the pores 0.003 to 0.005; length of the tubules 0.06 to 0.08, breadth of them 0.02 to 0.03.

Habitat.—Southern Pacific, Station 295, depth 1500 fathoms.

4. Caminosphæra dendrophora, n. sp. (Pl. 7, fig. 1).

Shell spherical, with a variable number (eight to twelve) of long cylindrical tubes, irregularly branched and scattered, nearly as long as the diameter of the shell. Every tube with two to six (commonly three to four) branches of different sizes. Mouth of the branches dilated, funnel-like; the edges irregularly dentated or lacerated. Pores between the tubes half as broad as these, irregularly roundish, twice as broad as their bars. Ten to twelve pores in the half meridian of the shell.

Dimensions.—Diameter of the shell 0.12 to 0.15, of the pores 0.006 to 0.01; length of the tubules 0.1 to 0.13, breadth of them 0.02 to 0.025.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 40. Solenosphæra,^[38] n. gen.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated wall; outer mouth of the tubuli truncated, smooth.

The genus Solenosphæra differs from Siphonosphæra in the fenestration of the external radial tubes. A large number of shells, appertaining to this genus, were already described by Ehrenberg, and disposed in five different genera corresponding to the different numbers of the tubuli:—Disolenia with two tubes, Trisolenia with three tubes, Tetrasolenia with four tubes, Pentasolenia with five tubes, Polysolenia with six or more tubes. All these five genera are without value, as those different numbers of tubes occur frequently intermingled in the individual cells of one and the same colony, wherever the form and structure of the tubes is inherited with sufficient constancy to determine the species.

Subgenus 1. Solenosphactra, Haeckel.

Definition.—Tubuli of the shell cylindrical or nearly cylindrical, the outer and inner apertures nearly of the same size.

1. Solenosphæra variabilis, Haeckel.

Tetrasolenia quadrata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. x. fig. 20.

Shell quite irregular roundish or polyhedral, with roundish pores of different size. Ten to fifteen pores in the half meridian of the shell, two to three times as broad as the bars. Porous tubuli of the shell in variable number (in one and the same colony), three to nine, mostly four to six; cylindrical or subcylindrical or somewhat conical, two to three times as broad as long, not longer than the half radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell (or somewhat smaller), about as large as the truncated outer aperture. This species is closely related to Collosphæra polyedra (p. 97), and may be derived from it by a short tube-like prolongation of the larger apertures.

Dimensions.—Diameter of the shell 0.1 to 0.16, of the pores 0.005 to 0.015; length of the tubules 0.02 to 0.03, breadth of them 0.04 to 0.06.

Habitat.—Central area of the Tropical Pacific, Stations 270, 271, 272, depths 2425 to 2925 fathoms.

2. Solenosphæra pandora, n. sp. (Pl. 7, figs. 10, 11).

Shell irregular roundish or subglobular, with roundish pores of different sizes, mostly somewhat broader than the bars. About twelve to sixteen pores on the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), one to six, mostly three to four; cylindrical or nearly cylindrical, somewhat longer than broad, not longer than the radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell, and a little smaller than the truncated outer aperture.

Dimensions.—Diameter of the shell 0.07 to 0.1, of the pores 0.003 to 0.006; length of the tubuli 0.03 to 0.05, breadth of them 0.02 to 0.03.

Habitat.—Central area of the Tropical Pacific, Stations 266 to 274, depths 2350 to 2925 fathoms.

3. Solenosphæra megalactis, Haeckel.

Trisolenia megalactis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 301, Taf. viii. fig. 19.

Shell irregularly polyhedrical, with very small roundish pores, scarcely half as broad as the bars. Only eight to ten pores on the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), two to five, mostly three or four; cylindrical, about as long as the radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell, and quite as broad as the truncated outer aperture.

Dimensions.—Diameter of the shell 0.07 to 0.09, of the pores 0.002 to 0.004, of the bars 0.005 to 0.009; length of the tubuli 0.03 to 0.04, breadth of them 0.02.

Habitat.—Pacific; California, Philippine Sea, Ehrenberg; Stations 256 to 285, depths 310 to 3000 fathoms.

4. Solenosphæra serpentina, n. sp. (Pl. 7, fig. 7).

Shell nearly spherical, with very small circular pores, scarcely one-third or one-fourth as broad as the bars. Only five to seven pores in the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), two to nine, mostly seven or eight; cylindrical, somewhat curved or contorted, once and a half or twice as long as the diameter of the shell, with few very small and widely scattered pores. Inner and outer aperture of the tubuli have the same diameter, about one-fifth or one-fourth that of the shell. (This species is closely allied to Siphonosphæra serpula, but is distinguished from it by the long tortuous tubuli and the small scarce pores.)

Dimensions.—Diameter of the shell 0.08 to 0.1, of the pores 0.001 to 0.002, of the bars 0.004 to 0.008; length of the tubuli 0.12 to 0.18, breadth of them 0.02 to 0.025.

Habitat.—North-eastern Pacific, between Sandwich Islands and California, Haltermann, surface.

Subgenus 2. Solenosphenia, Haeckel.

Definition.—Tubuli of the shell more or less conical, the inner aperture much larger than the outer aperture.

5. Solenosphæra venosa, Haeckel.

Tetrasolenia venosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 301, Taf. vii. fig. 22.

Shell irregular polyhedral or roundish, with a delicate network of large irregular polyhedral meshes, five to ten times as broad as the thin bars. Eight to twelve meshes on the half meridian of the shell. Fenestrated tubuli of the shell of variable number (in one and the same colony), one to five, commonly three or four, shaped like a short truncated cone, about half as long as broad on its base, shorter than the radius of the shell. Inner aperture of the cone nearly as broad as the half radius of the shell, about twice as broad as the truncated outer aperture.

Dimensions.—Diameter of the shell 0.07 to 0.12, of the pores 0.008 to 0.016, of the bars 0.001; length of the tubuli 0.02 to 0.03, inner aperture 0.03 to 0.04, outer aperture 0.02 to 0.03.

Habitat.—Indian Ocean, Sunda Strait, Rabbe.

6. Solenosphæra ascensionis, n. sp. (Pl. 7, fig. 9).

Shell somewhat irregular, subspherical, with polygonal pores of different size. Twelve to fifteen pores in the half meridian of the shell, two to eight times as broad as their bars. Porous tubuli of the shell of variable number (in one and the same colony), three to nine, mostly five to seven; conical or nearly cylindrical, irregular, about as long as broad at their base. Inner aperture of the tubuli two to four times as broad as the broadest pores, and double as broad as the truncated circular outer aperture.

Dimensions.—Diameter of the shell 0.1 to 0.12, of the pores 0.004 to 0.018, of the bars 0.002, length of the tubuli 0.04, inner aperture 0.04, outer 0.02.

Habitat.—South Atlantic, near Ascension Island, Station 343, surface.

Subgenus 3. Solenosphyra, Haeckel.

Definition.—Tubuli of the shell funnel-like, the outer aperture much larger than the inner.

7. Solenosphæra cornucopia, n. sp. (Pl. 7, fig. 8).

Shell spherical or subspherical, with roundish pores of different size. Ten to twelve pores in the half meridian of the shell, two to three times as broad as the bars. Porous tubuli of the shell of variable number (in one and the same colony), four to eight, mostly five to seven, funnel-like, about as long as the diameter of the shell. Inner aperture of the tubuli commonly two-thirds or three-fourths as broad as the radius of the shell (or somewhat smaller), only one-half or two-thirds as broad as the dilated and truncated outer aperture.

Dimensions.—Diameter of the shell 0.07 to 0.09, of the pores 0.006 to 0.018; length of the tubuli 0.06 to 0.08, diameter of the inner aperture 0.04 to 0.05, of the outer 0.06 to 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

8. Solenosphæra amalthea, n. sp.

Shell irregular roundish or spherical, with small circular pores of different size. Fifteen to twenty pores in the half meridian of the shell, but still not as broad as the bars. Porous tubuli of the shell of variable number (in one and the same colony), three to six, commonly four or five, funnel-like, about as long as the radius of the shell. Inner aperture of the tubuli about half as broad as the radius of the shell, only one-half or one-third as broad as the truncated outer aperture. (This species is intermediate between the preceding and Siphonosphæra chonophora, Pl. 6, fig. 5.)

Dimensions.—Diameter of the shell 0.09 to 0.11, of the pores 0.002 to 0.004, of the bars 0.003 to 0.006; length of the tubuli 0.05 to 0.06; diameter of the inner aperture 0.02 to 0.03, of the outer aperture 0.05 to 0.07.

Habitat.—Western part of the South Atlantic, Station 325, surface.

Genus 41. Otosphæra,^[39] n. gen.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated walls; outer mouth of the tubuli armed with a single tooth.

The genus Otosphæra differs from Solenosphæra by the single tooth on the external mouth of the tubuli, from Mazosphæra by the fenestration of the walls of the tubuli.

1. Otosphæra polymorpha, n. sp. (Pl. 7, fig. 6).

Shell quite irregular, polyhedral or roundish, very variable in size and form, with numerous very small pores, much smaller than the bars. Twenty to thirty pores in the half meridian of the shell. Porous tubuli of the shell commonly in variable number (one to four), but sometimes constant in number (one, two, three, or four) in the one and same colony. Tubuli irregular conical, commonly about as long as the radius of the shell; their outer aperture obliquely truncated, on one side prolonged into one large, prominent, bill-like, curved, acute tooth.

Dimensions.—Diameter of the shell 0.12 to 0.15, of the pores 0.001 to 0.002; length of the tubuli 0.06 to 0.08, inner aperture 0.03, outer aperture 0.02.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

2. Otosphæra auriculata, n. sp. (Pl. 7, fig. 5).

Shell quite irregular, of extremely variable form, now inclining to roundish, now to polyhedral, with very numerous small pores, irregularly formed and distributed. Twelve to twenty-four pores in the half meridian of the shell, of very different size, for the most part larger than the bars. Porous tubuli of the shell of variable number (in one and the same colony), one to five, mostly three or four, of conical form, irregularly formed and scattered, commonly about half as long as the radius of the shell. Outer aperture of the tubuli obliquely truncated, with one large prominent, often curved, acute tooth.

Dimensions.—Diameter of the shell 0.1 to 0.2, of the pores 0.003 to 0.005; length of the tubuli 0.01 to 0.05, inner aperture 0.04, outer aperture 0.03.

Habitat.—Central Tropical Pacific, Stations 268 to 272, depths 2425 to 2925 fathoms.

Genus 42. Coronosphæra,^[40] n. gen.

Definition.—Collosphærida with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated walls; outer mouth of the tubuli armed with a coronal of spines.

The genus Coronosphæra differs from Solenosphæra by the coronated mouth of the tubuli, from Trypanosphæra by the fenestration of the walls of the tubuli.

1. Coronosphæra diadema, n. sp. (Pl. 7, fig. 3).

Shell spherical or subspherical, with a variable number (fifteen to twenty) of short, coronal-like tubules, irregularly scattered, about half as long as the radius of the shell. Outer aperture of the tubuli irregularly dentated, a little dilated, and not much broader than the inner aperture, one-half or one-third as broad as the shell radius. Pores of the shell and of the tubuli circular or roundish, very irregularly scattered, mostly one-half or one-third as broad as the bars.

Dimensions.—Diameter of the shell 0.11 to 14, of the pores 0.002 to 0.004, of the bars 0.006 to 0.012; length of the tubuli 0.03, inner aperture 0.02 to 0.03, outer aperture 0.03 to 0.04.

Habitat.—Central Pacific, Stations 268 to 270, depths 2550 to 2925 fathoms.

2. Coronosphæra calycina, n. sp. (Pl. 7, fig. 4).

Shell spherical or subspherical, with a variable number (eight to twelve) of large, funnel-like tubules, irregularly scattered, about as long as the radius of the shell. Outer aperture of the tubuli irregularly dentated, much dilated, somewhat broader than the shell radius, three to four times as broad as the inner circular aperture. Pores of the shell and of the tubuli circular or roundish, of very different size, one to three times as broad as the bars.

Dimensions.—Diameter of the shell 0.1 to 0.3, of the pores 0.003 to 0.01, of the bars 0.002 to 0.004; length of the tubuli 0.1, inner aperture 0.02 to 0.03, outer aperture 0.06 to 0.18.

Habitat.—Central Pacific, Stations 271, 272, depths 2425 and 2600 fathoms respectively.

3. Coronosphæra convolvulus, n. sp.

Shell irregular roundish, with a variable number (five to ten) of long, curved tubules, about as long as the shell diameter. The inner half of the tubuli is narrow, cylindrical; the outer half funnel-like dilated, similar to the flower of Convolvulus. The outer aperture is elegantly dentated, five to six times as broad as the inner aperture. Pores of the shell and of the tubuli very irregular roundish, about as broad as the bars.

Dimensions.—Diameter of the shell 0.08 to 0.09, of the pores and bars 0.004 to 0.008; length of the tubuli 0.07 to 0.1, inner aperture 0.01, outer aperture 0.05.

Habitat.—Tropical Atlantic, Station 347, surface.

Subfamily Clathrosphærida, Haeckel, 1881, Prodromus, p. 472.

Definition.—Collosphærida with a double lattice-shell around every central capsule of the cœnobium; both concentric shells connected by irregular or subradial beams, commonly solid or lamellar staffs, rarely hollow tubes.

Genus 43. Clathrosphæra,^[41] Haeckel, 1881, Prodromus, p. 472.

Definition.—Collosphærida with a double lattice-shell around every central capsule of the cœnobium; surface of the outer shell smooth.

The genus Clathrosphæra (with smooth surface) and the following Xanthiosphæra (with spiny surface) form together the small subfamily, Clathrosphærida, different from the other Collosphærida by the double lattice-shell. From the surface of the inner primary shell arise either solid spines or hollow tubes, which unite by the anastomosis of irregular branches and so form the outer secondary shell, often very incomplete and irregular. All Clathrosphærida seem to inhabit great depths.

Subgenus 1. Clathrosphærula, Haeckel.

Definition.—The connecting staffs between both shells are hollow tubes (derived from Siphonosphæra).

1. Clathrosphæra circumtexta, n. sp. (Pl. 8, fig. 6).

Inner shell spherical, with irregular roundish large meshes, now broader now smaller than their bars. Eight to ten meshes in the half meridian of the shell. All these meshes are prolonged into short cylindrical hollow tubes, about as long as broad, somewhat constricted in the middle. From the margins of the outer openings of these tubes proceed very numerous and delicate siliceous filaments, which all lie on the same spherical face, branch, anastomose, and twine over the openings and the intervals between them, forming a very thin, arachnoid spherical outer shell. The meshes of this are quite irregular polygonal, of very different size and form. The radius of the inner shell bears to that of the outer a ratio = 5 : 6.

Dimensions.—Diameter of the inner shell 0.11 to 0.13, of the outer 0.13 to 0.16; meshes of the inner shell 0.005 to 0.02, of the outer 0.005 to 0.04.

Habitat.—North Pacific, Stations 238 to 253, depths 2050 to 3950 fathoms.

Subgenus 2. Clathrosphærium, Haeckel.

Definition.—The connecting staffs between the two shells are solid rods or lamellar spines (derived from Acrosphæra).

2. Clathrosphæra arachnoides, n. sp. (Pl. 8, fig. 7).

Inner shell spherical, with irregular roundish meshes, two or three times as broad as the bars. Ten to twelve meshes in the half meridian of the shell. From its surface arise numerous conical radial spines (with base often fenestrated), which at equal distances from the surface send out lateral branches. All these branches lie on a spherical face, and form by communications the irregular, very delicate, arachnoid network of the outer shell, quite unlike that of the inner, with large polygonal meshes of very different size. Eight to sixteen meshes in the half meridian of the shell. Surface of the outer shell nearly spherical, somewhat uneven, like a spider's web. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

Dimensions.—Diameter of the inner shell 0.12 to 0.14, of the outer 0.15 to 0.18; pores of the inner shell 0.003 to 0.02, of the outer 0.01 to 0.04.

Habitat.—Central area of the Tropical Pacific, Station 268, depth 2900 fathoms.

3. Clathrosphæra lamellosa, n. sp. (Pl. 8, fig. 8).

Inner shell spherical or subspherical, with irregular roundish meshes, about half as broad as the bars. Twelve to sixteen meshes in the half meridian of the shell. From its surface arise numerous oblique irregular staffs or broad and thin lamellæ, which branch quite irregularly, and by communications of the branches form the thin outer shell. This is quite irregular roundish or subspherical, very unlike the inner, with large polygonal meshes of different size, six to twelve in the half meridian of the shell. Bridges between the meshes very variable, now very thin filamentous, now very broad lamellar. Outer surface very uneven or tuberculated, but not spinous. The radius of the inner shell bears to that of the outer a ratio = 5 : 6.

Dimensions.—Diameter of the inner shell 0.1 to 0.13, of the outer 0.12 to 0.18; pores of the inner shell 0.003 to 0.009, of the outer 0.01 to 0.04.

Habitat.—Central area of the Tropical Pacific, Stations 270 to 274, depths 2350 to 2925 fathoms.

Genus 44. Xanthiosphæra,^[42] Haeckel, 1881, Prodromus, p. 472.

Definition.—Collosphærida with a double lattice-shell around every central capsule of the cœnobium; surface of the outer shell thorny or spiny.

The genus Xanthiosphæra differs from the foregoing Clathrosphæra by spines or thorns arising from the surface of the outer shell, commonly very irregular.

1. Xanthiosphæra capillacea, n. sp.

Inner shell spherical, with irregular polygonal meshes, three to five times as broad as their narrow bars. Six to eight meshes in the half meridian of the shell. From its surface arise at the nodes of the network numerous thin radial spines, which, at equal distances from the surface, send out lateral branches. All these branches lie on a spherical face, and form by communications the irregular delicate network of the outer shell, very like that of the inner, with large polygonal meshes, six to eight meshes in the half meridian of the shell. Surface of the outer shell covered with numerous straight spines, prolongations of the inner spines, but only half as long as these. The radius of the inner shell bears to that of the outer a ratio = 3 : 5.

Dimensions.—Diameter of the inner shell 0.1 to 0.12, of the outer 0.15 to 0.19; pores of the inner shell 0.02 to 0.04 to 0.06, of the outer 0.04 to 0.06 to 0.08; length of the outer spines 0.01 to 0.02.

Habitat.—Central area of the Tropical Pacific, Station 263, depth 2650 fathoms.

2. Xanthiosphæra erinacea, n. sp. (Pl. 8, fig. 9).

Inner shell spherical, with irregular roundish meshes, one-half to two times as broad as the bars. Fifteen to twenty meshes in the half meridian of the shell. From its surface arise numerous thin radial spines, which at equal distances from the surface send out lateral branches. All these branches lie on the face of a sphere, and form by communications the irregular delicate network of the outer shell, very unlike that of the inner, with large polygonal meshes, twelve to twenty-four in the half meridian of the shell. Surface of the outer shell covered with numerous straight spines, prolongations of the inner spines, and of the same length. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

Dimensions.—Diameter of the inner shell 0.1 to 0.12, of the outer 0.13 to 0.16; pores of the inner shell 0.002 to 0.008, of the outer 0.01 to 0.03; length of the outer spines 0.02 to 0.03.

Habitat.—Central area of the Tropical Pacific, Stations 270, 272, depth 2925 and 2600 fathoms respectively.

3. Xanthiosphæra lappacea, n. sp. (Pl. 8, figs. 10, 11).

Inner shell spherical or subspherical, with very small roundish pores, quite irregularly scattered, one-fourth to three-fourth as broad as their bars. Ten to twenty pores in the half meridian of the shell. From its surface arise in an extremely irregular and variable manner numerous oblique spines, often curved, often lamellar, and perforated by pores, sometimes hollow, fenestrated cones. At different distances from the surface these spines send out lateral curved branches, which by communications form the delicate and very irregular network of the outer shell. This network is often incomplete and very unlike that of the inner shell, with large polygonal meshes, six to eighteen in the half meridian of the shell. Surface of the outer shell covered with numerous small, curved, and oblique spines, prolongations of the inner spines, but scarcely one-third to one-half as long as these. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

Dimensions.—Diameter of the inner shell 0.08 to 0.12, of the outer 0.11 to 0.15; pores of the inner shell 0.001 to 0.009, of the outer 0.01 to 0.04; length of the outer spines 0.005 to 0.009.

Habitat.—Central area of the Tropical Pacific, Stations 263 to 274, depths 2350 to 3000 fathoms.

Family VII. Stylosphærida, Haeckel (Pls. 13-17).

Stylosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with two radial spines on the surface of the spherical shell, opposite in one axis; living solitary (not associated in colonies).

The family Stylosphærida comprises a large number of very common Sphæroidea, and is distinguished from all others by the possession of two radial spines which are placed in one axis of the spherical shell.^[43] By the expression of this "main axis" as a solid rod they form the transition to the Prunoidea, in which the whole shell is more or less transformed according to this "monaxial growth." But in these latter the shell, as well as the central capsule, becomes ellipsoidal, prolonged in one axis, whilst in the former they remain spherical. However, the distinction of both nearly allied groups is sometimes difficult.

The most simple Stylosphærida are the Xiphostylida, with one single spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Stylosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells: two in the Sphærostylida, three in the Amphistylida, four in the Cromyostylida, five or more in the Caryostylida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated spheres. In a sixth subfamily, in the Spongostylida, the shell is wholly or partially composed of a spongy irregular wicker-work, with or without a medullary shell in the centre.

Both the radial spines in all Stylosphærida are opposed normally in one axis; but in many species besides the normal form occur individual abnormalities, in which the two spines are not accurately opposed in this main axis, but placed in two different axes, intersecting at a smaller or larger angle. In the majority of the Stylosphærida both opposite spines have the same size and form; but in some genera they are more or less different, often in a very striking degree. The same differences occur in the nearly allied groups of Prunoidea, in the Ellipsida and Druppulida.

The distal ends of both spines are commonly free; but in the small group of Saturnalida (Saturnalis with one single shell, Saturnulus with two concentric shells, Saturninus with three concentric shells) the distal ends of both spines are united, at equal distances from the centre, by a circular or elliptical ring. This remarkable peculiarity occurs in no other group of Sphæroidea, and consequently brings the Saturnalida into close relation with the Discoidea.

Synopsis of the Genera of Stylosphærida.

I. Subfamily Xiphostylida. (Spherical shell simple.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Polar spines free, without connecting ring on the distal ends.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Both spines equal,	45. Xiphosphæra.
				Spines different in size or form,	46. Xiphostylus.
		Both polar spines united by a circular or elliptical ring,			47. Saturnalis.
II. Subfamily Sphærostylida. (Two concentric spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Polar spines free.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Both spines equal,	48. Stylosphæra.
				Spines different in size or form,	49. Sphærostylus.
		Both polar spines united by a circular or elliptical ring,			50. Saturnulus.
III. Subfamily Amphistylida. (Three concentric spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Polar spines free.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Both spines equal,	51. Amphisphæra.
				Spines different in size or form,	52. Amphistylus.
		Both polar spines united by a circular or elliptical ring,			53. Saturninus.
IV. Subfamily Cromyostylida. (Four concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Polar spines free.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Both spines equal,	54. Stylocromyum.
				Spines different,	55. Cromyostylus.
V. Subfamily Caryostylida. (Five or more concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Polar spines free.		Both spines equal,	56. Caryostylus.
VI. Subfamily Spongostylida. (Spherical shell partially or wholly of a spongy structure.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Shell a solid spongy sphere without central medullary shell,			57. Spongolonchis.
		In the centre of the spongy sphere one or two medullary shells.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	One central medullary shell,	58. Spongostylus.
				Two concentric medullary shells,	59. Spongostylidium.

Subfamily Xiphostylida, Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.—Stylosphærida with one simple spherical lattice-shell.

Genus 45. Xiphosphæra,^[44] Haeckel, 1881, Prodromus, p. 450.

Definition.—Stylosphærida with one single lattice-sphere and two free spines of equal size and form.

The genus Xiphosphæra is the most simple form of all Stylosphærida, and may be regarded as the common ancestral form of this family. On the surface of a simple spherical lattice-shell, enclosing the central capsule, arise two equal, free, radial spines, opposite to each other on the poles of one axis.

Subgenus 1. Xiphosphærantha, Haeckel.

Definition.—Pores of the spherical shell regular, of nearly equal size and form; surface smooth or a little rough, without spines or thorns (other than the two polar spines).

1. Xiphosphæra planeta, n. sp.

Pores regular, hexagonal, eight to nine times as broad as the thin bars. Ten to twelve pores on the half equator. Shell very thin walled; surface smooth. Polar spines three-sided pyramidal, about as long as the axis of the sphere, as broad at the base as one pore.

Dimensions.—Diameter of the sphere 0.12 to 0.13, pores 0.016 to 0.018, bars 0.002; length of the polar spines 0.1 to 0.15, basal thickness 0.02.

Habitat.—Pacific, central area, surface; Stations 271 to 274, depths 2425 to 2750 fathoms.

2. Xiphosphæra gæa, n. sp. (Pl. 14, fig. 5).

Pores regular, circular, with prominent hexagonal crests between them. On the half equator ten to twelve pores, of the same breadth as the crested bars. Shell thin walled; surface smooth. Polar spines three-sided prismatic, about twice as long as the axis of the sphere, twice as broad at the base as one pore.

Dimensions.—Diameter of the sphere 0.07 to 0.09, pores and bars 0.005; length of the polar spines 0.15 to 0.2, basal thickness 0.01.

Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.

3. Xiphosphæra venus, n. sp. (Pl. 14, fig. 2).

Pores regular, circular, with prominent hexagonal frames. On the half equator fifteen to eighteen pores, of the same breadth as the bars. Shell very thick walled; surface smooth, honeycomb-like. Polar spines conical, smooth, about as long as the axis of the shell, twice as broad at the base as one pore.

Dimensions.—Diameter of the sphere 0.12 to 0.13, pores and bars 0.005; thickness of the shell wall 0.013; length of the polar spines 0.12 to 0.15, basal breadth 0.01.

Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.

4. Xiphosphæra luna, n. sp.

Pores regular, circular, hexagonally lobed or rosette-shaped, three times as broad as the bars. Ten to twelve pores on the half equator. Shell thick walled; surface smooth. Polar spines three-sided pyramidal, one to two times as long as the axis of the shell, as broad at the base as one pore (very similar to Xiphostylus phasianus, Pl. 13, fig. 9, but different in the equal size and similar form of the two large polar spines).

Dimensions.—Diameter of the sphere 0.12, pores 0.015, bars 0.005; length of the polar spines 0.1 to 0.2, basal breadth 0.02.

Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.

5. Xiphosphæra hebe, n. sp.

Pores regular, circular, three times as broad as the bars. On the half equator sixteen to twenty pores. Shell thick walled; surface smooth. Polar spines conical or nearly cylindrical, about as long as the axis of the sphere, as broad at the base as two pores.

Dimensions.—Diameter of the sphere 0.1 to 0.13, pores 0.006, bars 0.002; polar spines 0.1 to 0.15 long, 0.01 thick.

Habitat.—Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.

6. Xiphosphæra maxima, n. sp.

Pores regular, circular, twice as broad as the bars, funnel-shaped. Twenty to thirty pores on the half equator. Shell very thick walled; surface smooth. Polar spines three-sided pyramidal, about as long as the radius of the sphere, as broad at the base as two pores.

Dimensions.—Diameter of the sphere 0.22 to 0.35, pores 0.008 to 0.01, bars 0.005; polar spines 0.1 to 0.15 long, 0.02 thick.

Habitat.—Equatorial Atlantic, Station 347, depth 2250 fathoms.

7. Xiphosphæra euphrosyne, n. sp.

Pores regular, circular, about as broad as the bars, double contoured. Eight to ten on the half equator. Shell thin walled; surface smooth. Polar spines conical, about as long as the radius of the sphere, as broad at the base as one pore.

Dimensions.—Diameter of the sphere 0.12 to 0.15, pores and bars 0.02; polar spines 0.06 to 0.09 long, 0.02 thick.

Habitat.—South Atlantic, Station 323, depth 1900 fathoms.

Subgenus 2. Xiphosphærella, Haeckel.

Definition.—Pores of the spherical shell regular, of nearly equal size and form; surface thorny or spiny, covered with regularly distributed papillæ or thorns (in addition to the two large polar spines).

8. Xiphosphæra pallas, n. sp. (Pl. 14, fig. 4).

Pores regular, circular, separated by hexagonal elevated frames, the sharp crest of which is elegantly denticulated; in each corner of the hexagons (between three pores) is a short radial spine, about as long as one pore. On the half equator sixteen to twenty pores, of the same breadth as the bars. Shell thick walled; whole surface spiny. Polar spines cylindrical, at the apex conical, about as long as the axis of the sphere, three to four times as broad as one pore.

Dimensions.—Diameter of the sphere 0.1, pores and bars 0.005; length of the polar spines 0.07 to 0.11, thickness 0.015 to 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

9. Xiphosphæra flora, n. sp.

Pores regular, circular, with hexagonal frames, twice as broad as the bars. Ten to twelve pores on the half equator. Shell thin walled, with spiny surface; in each corner of the hexagons is one bristle-like radial spine twice as long as one pore. Polar spines three-sided prismatic, at the apex pyramidal, nearly twice as long as the axis of the sphere, as broad at the base as two pores (similar to Ellipsoxiphus palliatus, Pl. 14, fig. 7).

Dimensions.—Diameter of the sphere 0.15, pores 0.01, bars 0.005; length of the polar spines 0.2 to 0.25, breadth 0.02.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

10. Xiphosphæra juno, n. sp.

Pores regular, circular, as broad as the bars, funnel-shaped. Fifteen to twenty pores on the half equator. Shell thick walled, covered with bristle-like spines, about twice as long as one pore. Polar spines conical, thick, about as long as the axis of the sphere, twice as broad at the base as one pore.

Dimensions.—Diameter of the sphere 0.12, pores and bars 0.01; length of the polar spines 0.14, basal breadth 0.02.

Habitat.—Fossil in the Barbados rocks; living in the greatest depth of the Tropical Pacific, Station 225, depth 4475.

11. Xiphosphæra gigantea, n. sp.

Pores regular, circular, two to three times as broad as the bars; twenty-eight to thirty-two on the half equator. Shell thick walled, covered with short conical thorns. Polar spines three-sided pyramidal, about as long as the radius of the sphere, as broad at the base as three pores.

Dimensions.—Diameter of the sphere 0.25 to 0.3, pores 0.01, bars 0.004; polar spines 0.1 to 0.15 long, 0.03 broad.

Habitat.—Fossil in the Tertiary rocks of Barbados and Sicily (Cattanisetta).

Subgenus 3. Xiphosphærissa, Haeckel.

Definition.—Pores of the spherical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns (other than the polar spines).

12. Xiphosphæra ceres, n. sp.

Pores irregular, roundish, of different sizes, two to four times as broad as the bars. Sixteen to twenty pores on the half equator. Shell thin walled, with smooth surface. Polar spines conical, about as long as the axis of the sphere, very thick at the base.

Dimensions.—Diameter of the sphere 0.15 to 0.2, pores 0.004 to 0.008, bars 0.002; polar spines 0.18 to 0.24 long, at the base 0.02 thick.

Habitat.—North Atlantic, Station 353, surface.

13. Xiphosphæra clavigera, n. sp.

Pores irregular, roundish, double contoured, of very unequal size, two to seven times as broad as the bars; ten to twelve on the half equator. Shell thick walled; surface a little rough. Polar spines club-shaped, with prominent edges, about half as long as the axis of the sphere; thinner at both ends than in the middle. (Differs from Ellipsoxiphus claviger, Pl. 14, fig. 3, in the spherical shell and shorter spines.)

Dimensions.—Diameter of the sphere 0.2, pores 0.005 to 0.02, bars 0.003; polar spines 0.06 long, 0.02 broad.

Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.

Subgenus 4. Xiphosphæromma, Haeckel.

Definition.—Pores of the spherical shell irregular, of different size or form; surface thorny or spiny (besides the two large polar spines).

14. Xiphosphæra vesta n. sp. (Pl. 14, fig. 6).

Pores irregular, roundish, three to five times as broad as the bars; fourteen to sixteen on the half equator. Scattered on the surface of the thick-walled shell are from twenty to thirty strong three-sided pyramidal spines of unequal size, the largest twice as long as the largest pores. Polar spines very strong, nearly three-sided prismatic, with curved edges, nearly as long as the axis of the sphere and twice as broad as the largest pores.

Dimensions.—Diameter of the sphere 0.17, pores 0.01 to 0.02, bars 0.004; length of the polar spines 0.13, thickness 0.02 to 0.03.

Habitat.—Pacific, central area. Station 266, depth 2750 fathoms,

15. Xiphosphæra astræa, n. sp.

Pores irregular, roundish, one to two times as broad as the bars; ten to twelve on the half equator. Surface of the thick-walled shell covered with numerous short conical thorns. Polar spines cylindro-conical, one and a half to two times as long as the axis of the sphere.

Dimensions.—Diameter of the sphere 0.18, pores 0.01 to 0.015, bars 0.008; length of the polar spines 0.25 to 0.3, thickness 0.02.

Habitat.—Indian Ocean, surface; Ceylon, Haeckel.

Genus 46. Xiphostylus,^[45] Haeckel, 1881, Prodromus, p. 450.

Definition.—Stylosphærida with one single lattice-sphere and two free spines of different size or form.

The genus Xiphostylus differs from the foregoing Xiphosphæra in the unequal size or form of both polar spines, which become more or less differentiated.

Subgenus 1. Xiphostylantha, Haeckel.

Definition.—Pores of the spherical shell regular, of nearly equal size and form; surface smooth or a little rough, without spines or thorns.

1. Xiphostylus alcedo, n. sp. (Pl. 13, fig. 4).

Pores regular, circular, with elevated hexagonal frames, twice as broad as the bars. Eight to ten pores on the half equator. Surface smooth. Polar spines three-sided pyramidal, as broad at the base as one hexagon; the major spine four to five times as long as the minor, which is about equal to the radius of the sphere.

Dimensions.—Diameter of the sphere 0.12, pores 0.012, bars 0.006; length of the major polar spine 0.16 to 0.2, of the minor 0.04 to 0.06, basal breadth 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475.

2. Xiphostylus phasianus, n. sp. (Pl. 13, fig. 9).

Pores regular, circular, twice as broad as the bars. Eight to ten pores on the half equator. Outer opening of each pore elegantly lobed, with eight indentations. Surface a little rough. Polar spines very unequal; major spine sword-like, sharply edged, about as long as the diameter of the sphere; minor spine scarcely half so long, pommel-shaped, with nine (?) wing-like edges.

Dimensions.—Diameter of the sphere 0.13, inner circular opening of the pores 0.01, outer eight-lobed opening 0.015, bars 0.005; length of the major polar spine 0.14, of the minor 0.06, breadth 0.03.

Habitat.—Australian Sea, Station 162, surface.

3. Xiphostylus motacilla, n. sp.

Pores regular, circular, three times as broad as the bars; sixteen to twenty on the half equator. Surface smooth. Polar spines compressed, two-edged, at the base three to four times as broad as one pore; the major spine somewhat longer than the diameter of the shell, the minor scarcely one-third or one-half as long.

Dimensions.—Diameter of the sphere 0.14, pores 0.006, bars 0.002; length of the major spine 0.16 to 0.18, of the minor 0.05 to 0.07, basal breadth 0.02.

Habitat.—Indian Ocean, Zanzibar, 2200 fathoms, Pullen.

4. Xiphostylus gallus, n. sp.

Pores regular, circular, five times as broad as the bars. Twelve to sixteen pores on the half equator. Surface smooth. Polar spines very unequal; the major conical spine one and a half to three times as long as the diameter of the sphere; the minor pommel-shaped, scarcely one-third as long (length of both spines very variable).

Dimensions.—Diameter of the sphere 0.13, pores 0.01, bars 0.002; length of the major spine 0.2 to 0.4, of the minor 0.05 to 0.08.

Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.

5. Xiphostylus alauda, n. sp. (Pl. 14, fig. 15).

Lithomespilus alauda, Haeckel, 1881, Prodrom. et Atlas, loc. cit.

Pores subregular, circular, three to four times as broad as the bars; fifteen to eighteen on the half equator. Surface a little rough. Polar spines irregularly conical or pyramidal, scarcely as long as the radius of the sphere; one spine simple, the other composed of a bunch of four or five spines united at the base.

Dimensions.—Diameter of the sphere 0.11, pores 0.01, bars 0.003; length of the polar spines 0.03 to 0.05, basal breadth 0.02.

Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.

6. Xiphostylus anhinga, Haeckel.

Rhabdolithis pipa, Bury, 1862, Polycystins of Barbados, pl. iii. fig. 4.

Pores subregular, circular, about the same breadth as the bars; eight to ten on the half equator. Surface smooth or a little rough. Polar spines cylindrical, very irregularly curved like S or contorted, the major three to six times as long as the diameter of the sphere, the minor scarcely one-fourth as long as the former, at the end truncated.

Dimensions.—Diameter of the sphere 0.07, pores and bars 0.005; length of the major polar spine 0.2 to 0.4, of the minor 0.06 to 0.09, basal breadth 0.01.

Habitat.—Fossil in the Barbados rocks.

Subgenus 2. Xiphostyletta, Haeckel.

Definition.—Pores of the spherical shell regular, of nearly equal size and form; surface thorny or spiny (other than the two large polar spines).

7. Xiphostylus cuculus, n. sp.

Pores regular, circular, hexagonally framed, three times as broad as the bars; ten to twelve on the half equator. Surface thorny, between every three pores a short conical thorn. Polar spines three-sided prismatic, the major somewhat longer than the diameter of the sphere, the minor scarcely one-third as long, pommel-shaped.

Dimensions.—Diameter of the sphere 0.17, pores 0.012, bars 0.004; length of the major polar spine 0.2, of the minor 0.05, basal breadth 0.015.

Habitat.—South Atlantic, surface; Station 335, depth 1425 fathoms.

8. Xiphostylus trochilus, n. sp. (Pl. 13, fig. 10).

Pores regular, circular, four times as broad as the bars; eight to nine on the half equator. Polar spines cylindrical, the major somewhat longer than the axis of the sphere, the minor shorter, surrounded by a group of from four to eight shorter conical spines. Surface of the opposite hemisphere smooth, without by-spines.

Dimensions.—Diameter of the sphere 0.07 to 0.08, pores 0.01, bars 0.0025.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

9. Xiphostylus picus, n. sp. (Pl. 14, fig. 13).

Lithomespilus picus, Haeckel, 1881, Prodrom. et Atlas.

Pores regular, circular, twice as broad as the bars; sixteen to eighteen on the half equator. Polar spines cylindrical, conical at the apex, the major once and a half to twice as long as the diameter of the shell, the minor scarcely half so long; around the latter a group of twelve to twenty shorter conical spines, irregularly scattered. Surface of the other hemisphere smooth.

Dimensions.—Diameter of the sphere 0.13, pores 0.006, bars 0.003; length of the major polar spine 0.2 to 0.24, of the minor 0.08 to 0.09, basal breadth 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 3. Xiphostylissa, Haeckel.

Definition.—Pores of the spherical shell irregular, of unequal size or form; surface smooth or a little rough, without thorns.

10. Xiphostylus trogon, n. sp. (Pl. 14, fig. 12).

Lithomespilus trogon, Haeckel, 1881, Prodrom. et Atlas.

Pores irregular, roundish or subcircular, two to three times as broad as the bars; ten to twelve on the half equator. Surface smooth. Major polar spine three-sided prismatic, once and a half to twice as long as the axis of the sphere; minor spine quite rudimentary, scarcely longer than broad, but surrounded by a group of from three to six similar short spines.

Dimensions.—Diameter of the sphere 0.1, pores 0.005 to 0.015, bars 0.005 to 0.008; length of the major spine 0.15 to 0.18, of the minor 0.01 to 0.02, basal breadth 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

11. Xiphostylus falco, n. sp. (Pl. 13, fig. 14).

Pores irregular, roundish, two to five times as broad as the bars; sixteen to eighteen on the half equator. Surface smooth. Polar spines cylindrical, very stout, nearly half as thick as the radius of the shell; major spine two to four times as long as the diameter of the shell; minor spine obliquely inserted, scarcely longer than the diameter, divided at the end into two short, hook-shaped, curved branches.

Dimensions.—Diameter of the sphere 0.08, pores 0.002 to 0.005, bars 0.001; breadth of the spines 0.02, length of the major spine 0.15 to 0.2, of the minor 0.09.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

12. Xiphostylus alca, n. sp. (Pl. 13, fig. 13).

Pores irregular, roundish, two to six times as broad as the bars; six to eight on the half equator. Each pore with three to six lobes, composed of three to six confluent smaller pores. Surface smooth. Major spine conical, curved, somewhat longer than the axis of the sphere; minor spine somewhat shorter, pommel-like, edged.

Dimensions.—Diameter of the sphere 0.07, pores 0.01 to 0.02, bars 0.003; length of the major spine 0.08, of the minor 0.06, basal thickness 0.02.

Habitat.—Indian Ocean, Sunda Strait, Rabbe, surface.

13. Xiphostylus edolius, n. sp. (Pl. 13, fig. 5).

Pores irregular, roundish, composed of two to six smaller confluent pores. On the half equator six to eight large pores, and twenty to thirty small pores; bars between the smaller very thin. Surface a little rough. Major polar spine conical, S-shaped, about twice as long as the axis of the shell; minor spine pommel-shaped, edged, scarcely as long as its radius.

Dimensions.—Diameter of the sphere 0.12, large pores 0.01 to 0.03, small pores 0.004 to 0.008, bars 0.001 to 0.004; length of the major spine 0.2, of the minor 0.05, basal breadth 0.02.

Habitat.—Central Pacific, Station 273, surface.

Subgenus 4. Xiphostylomma, Haeckel.

Definition.—Pores of the spherical shell irregular, of different size or form; surface thorny or spiny.

14. Xiphostylus emberiza, n. sp. (Pl. 13, fig. 11).

Pores irregular, roundish, one to four times as broad as the bars; six to eight on the half equator. Polar spines very unequal; major cylindrical, twice as long as the axis of the sphere; minor scarcely half as long, obliquely inserted, like a bird's head, surrounded by a group of ten to twenty smaller conical spines. Opposite hemisphere smooth.

Dimensions.—Diameter of the sphere 0.005, pores 0.002 to 0.008, bars 0.002; length of the major spine 0.09, of the minor 0.05, basal breadth 0.01.

Habitat.—South Atlantic, Station 332, surface.

15. Xiphostylus ardea, n. sp.

Pores irregular, roundish, one to three times as broad as the bars; twelve to sixteen on the half equator. Whole surface spiny. Major polar spine three-sided pyramidal, somewhat longer than the diameter of the sphere; minor scarcely so long as its half radius, pommel-like, edged.

Dimensions.—Diameter of the sphere 0.12, pores 0.003 to 0.01, bars 0.003; length of the major polar spine 0.15, of the minor 0.03, basal breadth 0.02.

Habitat.—North Atlantic, Station 64, surface.

Genus 47. Saturnalis,^[46] Haeckel, 1881, Prodromus, p. 450.

Definition.—Stylosphærida with one single lattice-sphere and two equal opposite spines, connected at the distal end by a circular or elliptical ring.

The genus Saturnalis (with simple lattice-sphere) and the two similar genera Saturnulus (with two concentric spheres) and Saturninus (with three spheres) form together the small peculiar group of Saturnalida, distinguished by a remarkable circular or elliptical ring, connecting the distal ends of the two equal opposite polar spines. This ring indicates a certain equatorial plane, and therefore brings these Sphæroidea into relation with the Discoidea.

Subgenus 1. Saturnalina, Haeckel.

Definition.—Ring smooth, without spines or thorns.

1. Saturnalis circularis, n. sp.

Pores of the spherical shell regular, circular, hexagonally framed, twice as broad as the bars. Ten to twelve pores on the half equator. Ring circular, smooth, its diameter three times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.07, pores 0.005, bars 0.0025; diameter of the circular ring 0.2, thickness of the axial beams and the ring 0.01.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Saturnalis annularis, n. sp. (Pl. 13, fig. 16).

Pores of the spherical shell regular, circular, with elevated hexagonal frames, of the same breadth as the bars. Sixteen to twenty pores on the half equator. Ring elliptical, smooth, somewhat constricted at the poles of the axis, its diameter three times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.09, pores and bars 0.005, major axis of the elliptical ring 0.27 to 0.3, minor axis 0.19 to 0.2; thickness of the ring and of the axial beams 0.01.

Habitat.—Pacific, central area, Stations 270 to 274, surface.

3. Saturnalis cyclus, n. sp.

Lithocircus mesocena, Bury, 1862, Polycystins of Barbados, pl. iii. fig. 1.

Pores of the spherical shell regular, circular, without hexagonal frames, twice as broad as the bars. Eight to ten pores on the half equator. Ring circular, smooth, its diameter four times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.07, pores 0.006, bars 0.003; diameter of the circular ring 0.28, thickness of the ring and both axial beams 0.01.

Habitat.—Fossil in the Barbados rocks.

4. Saturnalis circoides, n. sp. (Pl. 13, fig. 12).

Pores of the spherical shell irregular, roundish, often somewhat lobed, one to three times as broad as the bars; fifteen to twenty on the half equator. Ring circular, smooth, with four prominent edges, its diameter twice as great as that of the sphere. (The figured specimen is a young or not fully developed one; afterwards I found in the same locality other specimens with quite perfect rings, similar to the edged ring of Saturnulus annulus, Pl. 16, fig. 17.)

Dimensions.—Diameter of the sphere 0.09 to 0.1, pores 0.003 to 0.01, bars 0.004; diameter of the circular ring 0.2 to 0.24, thickness of the ring and the polar beams 0.01.

Habitat.—Indian Ocean; fossil in the Nicobar rocks; living at great depths near Zanzibar, 2200 fathoms, Pullen.

Subgenus 2. Saturnalium, Haeckel.

Definition.—Ring armed on the periphery with numerous spines or thorns.

5. Saturnalis trochoides, n. sp.

Haliomma species, Bury, 1862, Polycystins of Barbados, pl. xx. fig. 2.

Pores of the spherical shell subregular, circular, twice as broad as the bars. Twelve to sixteen pores on the half equator. Ring circular, armed with ten to twelve strong conical, irregular spines, its diameter twice as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.08, pores 0.006, bars 0.003; diameter of the circular ring 0.16; length of the radial spines 0.02 to 0.04; thickness of the ring and the axial beams 0.01.

Habitat.—Fossil in the Barbados rocks.

6. Saturnalis rotula, n. sp. (Pl. 13, fig. 15).

Pores of the spherical shell regular, circular, twice as broad as the bars; sixteen to twenty on the half equator. Ring circular, armed with fifteen to twenty strong, conical, irregular spines, partly simple, partly divided into two or three irregular branches; diameter of the ring two and a half times as great as that of the sphere.

Dimensions.—Diameter of the sphere 0.08, pores 0.004, bars 0.002; diameter of the circular ring 0.2, length of its spines 0.02 to 0.03; thickness of the ring and the radial beams 0.01.

Habitat.—North Pacific, Station 244, surface.

Subfamily Sphærostylida, Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Stylosphærida with two concentric, spherical lattice-shells.

Genus 48. Stylosphæra,^[47] Ehrenberg, 1847, Monatsber. d. Berlin Akad., p. 54.

Definition.—Stylosphærida with two concentric lattice-spheres and two free spines of equal size and similar form.

The genus Stylosphæra, the most simple form of the Sphærostylida, can be derived either from Xiphosphæra by duplication of the spherical shell, or from Carposphæra by development of two opposite polar spines. The inner or medullary shell is enclosed in the central capsule, whilst the outer or cortical shell lies outside it; the two are connected by two or more radial beams, piercing the wall of the capsule.

Subgenus 1. Stylosphærantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without spines or thorns.

1. Stylosphæra musa, n. sp.

Radial proportion of the two concentric spheres = 3 : 1. Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the thin bars; twelve on the half equator. Polar spines three-sided pyramidal, as long as the axis of the cortical shell, one-tenth as broad at the base.

Dimensions.—Diameter of the outer shell 0.2, pores 0.01, bars 0.003; diameter of the inner shell 0.06; length of the polar spines 0.2, basal breadth 0.02.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Stylosphæra urania, n. sp.

Radial proportion of the two shells = 4 : 1. Cortical shell thin walled, smooth; pores regular, circular, hexagonally framed, twice as broad as the bars; ten on the half equator. Polar spines conical, as long as the radius of the outer shell.

Dimensions.—Diameter of the cortical shell 0.24, pores 0.012, bars 0.006; medullary shell 0.06; length of the polar spines 0.12, basal breadth 0.024.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

3. Stylosphæra calliope, n. sp. (Pl. 16, fig. 6).

Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars. Each pore on its outer opening with eight regular lobules, flower-like. Nine to ten pores on the half equator. Polar spines three-sided pyramidal, with three strong prominent edges, about as long as the axis, as broad as one pore. (Sometimes, as in the figured specimen, one spine is smaller than the other; this variety, otherwise identical, may be called Sphærostylus calliope.)

Dimensions.—Diameter of the outer shell 0.12, pores 0.015, bars 0.005; inner shell 0.04; length of the polar spine 0.08 to 0.12, breadth 0.02.

Habitat.—Pacific, central area, Station 268, depth 2900 fathoms.

4. Stylosphæra clio, n. sp. (Pl. 16, fig. 7).

Radial proportion of the two shells = 2 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars; fourteen to sixteen on the half equator. Polar spines three-sided pyramidal, very robust, with thick prismatic edges, about as long as the axis of the cortical shell, one-third as broad at the base. (Sometimes, as in the figured specimen, one spine is greater than the other; this form may be called Sphærostylus clio.)

Dimensions.—Diameter of the outer shell 0.12, pores 0.01, bars 0.003; inner shell 0.06; length of the polar spines 0.08 to 0.12, basal breadth 0.03 to 0.04.

Habitat.—Pacific, central area; Station 272, depth 2600 fathoms.

5. Stylosphæra polyhymnia, n. sp.

Radial proportion of the two spheres = 3 : 1. Cortical shell very thin walled, smooth, with regular, circular pores, three times as broad as the bars; sixteen to twenty on the half equator. Polar spines cylindrical, pointed, once and a half to twice as long as the axis of the outer sphere, scarcely broader than one pore. The two spheres are connected only by the two opposite beams.

Dimensions.—Diameter of the outer shell 0.12 to 0.16, pores 0.006 to 0.009, bars 0.002 to 0.003; inner shell 0.04 to 0.05; length of the polar spines 0.18 to 0.22, breadth 0.01.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

6. Stylosphæra dixyphos, Haeckel.

Haliomma dixyphos, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83; Mikrogeol., Taf. xxii. fig. 31. Haliomma dixyphos, Haeckel, 1862, Monogr. d. Radiol. p. 433.

Radial proportion of the two spheres = 2 : 1. Cortical shell thin walled, smooth, with regular, circular pores, twice as broad as the bars; ten to twelve on the half equator. Polar spines about as long as the axis of the outer shell, three-sided pyramidal, at the base twice as broad as one pore. (The two spheres connected by four beams, two opposite in the main axis, two opposite in the equatorial axis.)

Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.05; inner shell 0.05; length of the polar spines 0.08 to 0.1, basal breadth 0.02.

Habitat.—South Atlantic, Station 332, surface; fossil in Tertiary rocks of Sicily.

Subgenus 2. Stylosphærella, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface thorny or spiny.

7. Stylosphæra setosa, Ehrenberg, 1872.

Stylosphæra setosa, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 320; Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. viii. fig. 15.

Radial proportion of the two shells = 2 : 1. Cortical shell thin walled, spiny; pores regular, hexagonal, four times as broad as the bars. Six to eight pores on the half equator. Polar spines conical, thin, scarcely as long as the radius of the cortical shell.

Dimensions.—Diameter of the cortical shell 0.1, pores 0.002, bars 0.005; medullary shell 0.05; length of the polar spines 0.04, basal breadth 0.01.

Habitat.—Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 206, depth 2100 fathoms.

8. Stylosphæra euterpe, n. sp.

Radial proportion of the two shells = 3 : 1. Cortical shell thin walled, spiny; pores regular, circular, with hexagonal frames, twice as broad as the bars; eight to ten on the half equator. Polar spines conical, as thick as one pore at the base, about as long as the axis of the cortical shell.

Dimensions.—Diameter of the cortical shell 0.12, pores 0.012, bars 0.006; medullary shell 0.04; length of the polar spines 0.1, basal breadth 0.012.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

9. Stylosphæra melpomene, n. sp. (Pl. 16, fig. 1).

Radial proportion of the two shells = 3 : 1. Cortical shell thin walled, spiny, with regular, circular pores, four times as broad as the bars; eight to ten on the half equator. Polar spines three-sided prismatic, pointed, as broad as one pore, only one-third as long as the axis of the sphere (the two shells connected by four thin beams, two opposite in the main axis, two in the equatorial axis).

Dimensions.—Diameter of the outer shell 0.12, pores 0.012, bars 0.003; inner shell 0.04; length of the polar spines 0.04, thickness 0.013.

Habitat.—Indian Ocean, Cocos Islands, Rabbe.

10. Stylosphæra hispida, Ehrenberg, 1854.

Stylosphæra hispida, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 246; Mikrogeol, Taf. xxxvi. fig. 26. Haliomma hispidum, Haeckel, 1862, Monogr. d. Radiol., p. 433.

Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, spiny, with regular, circular pores of the same breadth as the bars; ten to fifteen on the half equator. Polar spines three-sided prismatic, pointed, about as long as the axis of the outer sphere, nearly as broad at the base as the inner sphere. (Compare Sphærostylus hispidus; also Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1874, p. 259.)

Dimensions.—Diameter of the outer shell 0.1 to 0.12, pores and bars 0.004; inner shell 0.04; length of the polar spines 0.1 to 0.15, basal breadth 0.03.

Habitat.—Fossil in the Tertiary rocks of Sicily, Barbados, Nicobars, &c.

11. Stylosphæra liostylus, Ehrenberg, 1875.

Stylosphæra liostylus, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 3.

Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, thorny, with regular, circular pores, three times as broad as the bars; eight to ten on the half equator. Polar spines conical, once and a half to twice as long as the axis of the outer sphere, half as broad at the base as its radius. (This species, common in the Barbados rocks, is different from Sphærostylus liostylus, loc. cit., fig. 2, which Ehrenberg believed identical.)

Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.0035; inner shell 0.03; length of the polar spines 0.14 to 0.18, basal breadth 0.02.

Habitat.—Fossil in the Barbados rocks; living in the depths of the North Atlantic, Gulf Stream, Florida.

Subgenus 3. Stylosphærissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without thorns or spines.

12. Stylosphæra nana, n. sp. (Pl. 16, figs. 12, 13).

Radial proportion of the two spheres = 2 : 1. Cortical shell thick walled, somewhat irregular, smooth, with irregular, roundish pores, one to three times as broad as the bars; eight to ten on the half equator. Polar spines three-sided pyramidal, scarcely as long as the axis of the outer sphere, and nearly as broad at the base as its radius. (A very variable and irregular form.)

Dimensions.—Diameter of the outer shell 0.07 to 0.09, pores 0.003 to 0.009, bars 0.003; inner shell 0.03 to 0.04; length of the polar spines 0.04 to 0.07, basal breadth 0.03.

Habitat.—North Pacific, Stations 241 to 253, surface.

13. Stylosphæra jugata, n. sp.

Radial proportion of the two shells = 2 : 1. Cortical shell thick walled, smooth, with irregular, roundish, double-contoured pores, confluent in groups of two to six. On the half equator six to nine groups and fifteen to twenty pores; bars between them of very variable breadth. Polar spines very strong, three-sided pyramidal, twice as long as the axis of the outer sphere, half as broad at the base as its radius. (Nearly allied to Lithatractus jugatus, Pl. 16, fig. 2, but differs in the truly spherical form of both shells and the double length of the polar spines.)

Dimensions.—Diameter of the outer shell 0.15, pores 0.005 to 0.02; inner shell 0.07; length of the polar spines 0.25 to 0.3, basal breadth 0.03.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

14. Stylosphæra terpsichore, n. sp.

Radial proportion of the two shells = 3 : 1 or 4 : 1. Cortical shell thick walled, smooth, with irregular, roundish pores, one to three times as broad as the bars; fifteen to twenty-five on the half equator. Polar spines conical, about as long as the axis of the outer sphere, as broad at the base as the inner shell.

Dimensions.—Diameter of the outer shell 0.15 to 0.2, pores 0.005 to 0.02, bars 0.004 to 0.008; inner shell 0.05; length of the polar spines 0.15 to 0.25, basal breadth 0.05.

Habitat.—Western Indian Ocean, Zanzibar, depth 2200 fathoms, Pullen.

Subgenus 4. Stylosphæromma, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

15. Stylosphæra thalia, n. sp.

Radial proportion of the two shells = 2 : 1. Cortical shell thin walled, thorny, with irregular, roundish pores, two to four times as broad as the bars; eight to twelve on the half equator. Polar spines conical, one to one and a half times as long as the axis of the outer sphere, one-fourth to one-sixth as thick at the base. (Resembles Sphærostylus ophidium, Pl. 16, fig. 14, but differs in the straight regular conical polar spines, both of equal length and similar form.)

Dimensions.—Diameter of the outer shell 0.12, pores 0.01 to 0.02, bars 0.005; inner shell 0.06; polar spines 0.1 to 0.16 long, 0.03 broad.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

16. Stylosphæra erato, n. sp.

Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, thorny, with irregular, roundish pores, two to five times as broad as the bars; fourteen to eighteen on the half equator. Polar spines three-sided pyramidal, about as long as the axis of the outer sphere, one-fourth as broad as its radius. (Similar to Xiphosphæra vesta, Pl. 14, fig. 6.)

Dimensions.—Diameter of the outer shell 0.15, pores 0.008 to 0.015, bars 0.003; inner shell 0.05; polar spines 0.12 long, 0.02 broad.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

Genus 49. Sphærostylus,^[48] Haeckel, 1881, Prodromus, p. 451.

Definition.—Stylosphærida with two concentric lattice-spheres and two free spines, of different size or form.

The genus Sphærostylus differs from Stylosphæra in the different size or form of the two polar spines, and therefore has the same relation to it that Xiphostylus bears to Xiphosphæra.

Subgenus 1. Sphærostylantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without thorns.

1. Sphærostylus liostylus, Haeckel.

Stylosphæra liostylus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 2.

Cortical shell thin walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular, circular, twice as broad as the bars; ten to twelve on the half equator. Polar spines cylindrical, as broad as one pore, with conical apex; the minor spine about as long as the axis of the outer shell, the major three to four times as long.

Dimensions.—Diameter of the outer sphere 0.12, pores 0.12, bars 0.006; diameter of the inner sphere 0.04; length of the major polar spine 0.3 to 0.4, of the minor 0.1 to 0.15, breadth 0.012.

Habitat.—Fossil in the Barbados rocks.

2. Sphærostylus flexuosus, Haeckel.

Stylosphæra flexuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 5.

Cortical shell thick walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular circular, of the same breadth as the bars; eight to ten on the half equator. Polar spines cylindrical, S-like curved, irregular; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long. (In the figure of Ehrenberg the spines are broken off; I have found them myself constantly irregular and of unequal length, sometimes with conical apex.)

Dimensions.—Diameter of the outer sphere 0.08, pores and bars 0.006; inner sphere 0.03; length of the major polar spine 0.15 to 0.25, of the minor 0.07 to 0.09, breadth 0.02.

Habitat.—Fossil in the Barbados rocks.

3. Sphærostylus clio, n. sp.

Cortical shell thick walled, with smooth surface, twice as broad as the medullary shell; its network has regular, circular pores, three times as broad as the bars; sixteen to twenty on the half equator. Polar spines very strong, three-sided pyramidal; the major nearly twice as long as the axis of the outer sphere, the minor scarcely as long as its radius. (Nearly related to Stylosphæra clio, Pl. 16, fig. 7, but differs in the slender form and unequal length of the polar spines.)

Dimensions.—Diameter of the outer sphere 0.14, pores 0.01, bars 0.03; inner sphere 0.07; length of the major spine 0.25, of the minor 0.06, basal breadth 0.02.

Habitat.—Pacific, central area, Station 274, depth 2750 fathoms.

4. Sphærostylus hippocampus, n. sp. (Pl. 16, figs. 10, 11).

Cortical shell thick walled, with smooth surface and regular network; the pores circular, hexagonally-lobed, three times as broad as the bars; ten to twelve on the half equator. Medullary shell half as large, with very small circular pores, eight to ten on the half equator. Major polar spine scarcely as long as the axis of the outer shell, curved like a horn; minor spine scarcely half as long, pommel-like, edged. (Sometimes, by prolongation of the main axis, the spherical shells become ellipsoidal and thus the species is transformed into Druppatractus hippocampus.)

Dimensions.—Diameter of the outer sphere 0.08, pores 0.009, bars 0.003; inner sphere 0.04; length of the major spine 0.07, of the minor 0.03, breadth 0.02.

Habitat.—Pacific, central area, Station 270, depth 2925 fathoms.

Subgenus 2. Sphærostyletta, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and form; surface spiny or thorny.

5. Sphærostylus diadema, n. sp.

Cortical shell thick walled, spiny, twice as broad as the medullary shell, with regular, circular pores, twice as broad as the bars; eight to ten on the half equator. Major polar spine about as long as the axis of the outer sphere, three-sided pyramidal; minor spine scarcely half as long, pommel-shaped, edged. (Similar in general form to Xiphatractus glyptodon, Pl. 17, figs. 9, 10; but differs in the simple medullary shell, the spherical form of both shells, and the simple circular regular pores.)

Dimensions.—Diameter of the outer sphere 0.12, pores 0.014, bars 0.007; inner sphere 0.06; length of the major spine 0.13, of the minor 0.05, greatest breadth 0.04.

Habitat.—Southern Pacific, surface, Station 289.

Subgenus 3. Sphærostylissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough.

6. Sphærostylus cottus, n. sp.

Cortical shell thick walled, smooth, about twice as broad as the medullary shell, with irregular, roundish pores, scarcely larger than the bars; fifteen to twenty on the half equator. Polar spines conical, the major once and a half to twice as long as the axis of the outer sphere, the minor scarcely as long as its radius.

Dimensions.—Diameter of the outer sphere 0.14, pores and bars 0.008 to 0.012; inner sphere 0.065; length of the major spine 0.2 to 0.3, of the minor 0.05 to 0.07, basal breadth 0.03.

Habitat.—Northern Atlantic, Færöe Channel, surface, John Murray.

7. Sphærostylus trigla, n. sp.

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with irregular, roundish pores, two to three times as broad as the bars; ten to twelve on the half equator. Polar spines very unequal; the major three-sided pyramidal, one and a half times as long as the axis of the outer sphere; the minor scarcely as long as its radius, edged, pommel-like.

Dimensions.—Diameter of the outer sphere 0.12, pores 0.01 to 0.015, bars 0.005; inner sphere 0.04; length of the major spine 0.2, of the minor 0.05, breadth 0.03.

Habitat.—Northern Pacific, Station 241, depth 2300 fathoms.

Subgenus 4. Sphærostylomma, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

8. Sphærostylus ophidium, n. sp. (Pl. 16, figs. 14, 15).

Stylosphæra ophidium, Haeckel, 1878, Atlas, loc. cit.

Cortical shell thin walled, thorny, twice as broad as the medullary shell, with irregular, roundish pores; eight to ten on the half equator. Polar spines conical, more or less curved or S-shaped; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long.

Dimensions.—Diameter of the outer sphere 0.11, pores 0.01 to 0.017, bars 0.003 to 0.007; diameter of the inner sphere 0.06, pores 0.005 to 0.008, bars 0.002 to 0.004; length of the major polar spine 0.25, of the minor 0.1, basal breadth 0.03.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

Genus 50. Saturnulus,^[49] Haeckel, 1881, Prodromus, p. 451.

Definition.—Stylosphærida with two concentric lattice-spheres and two equal opposite spines, the distal ends of which are connected by a circular or elliptical ring.

The genus Saturnulus differs from the similar Saturnalis by the duplication of the spherical lattice-shell; the inner lies within, the outer without the central capsule.

1. Saturnulus circulus, n. sp.

Cortical shell smooth, twice as broad as the medullary shell, with regular, circular, hexagonally framed pores, of the same breadth as the bars; fourteen to sixteen on the half equator. Ring circular, smooth, without edges, its diameter three times as great as that of the sphere.

Dimensions.—Diameter of the outer sphere 0.08, pores and bars 0.004; of the inner sphere 0.04, of the ring 0.24.

Habitat.—Central Pacific, Station 272, surface.

2. Saturnulus annulus, n. sp.

Cortical shell smooth, three times as broad as the medullary shell, with regular, circular, hexagonally framed pores, of the same breadth as the bars; eighteen to twenty on the half equator. Ring elliptical, smooth, without edges, somewhat constricted at the poles of the minor axis, its major diameter four times as great as that of the sphere. Differs from Saturnalis annularis, Pl. 13, fig. 16, mainly in the possession of a medullary shell.

Dimensions.—Diameter of the outer sphere 0.1, pores and bars 0.005; inner sphere 0.033; major axis of the ring 0.4, minor 0.3.

Habitat.—North Pacific, Station 244, surface.

3. Saturnulus ellipticus, n. sp. (Pl. 16, fig. 16).

Cortical shell smooth, three times as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; sixteen to eighteen on the half equator. Ring elliptical, smooth, without edges, its major diameter three times as great as that of the sphere.

Dimensions.—Diameter of the outer sphere 0.09, pores 0.006, bars 0.002; inner sphere 0.03; major axis of the elliptical ring 0.28, minor 0.24; thickness of the ring and the axial beams 0.008.

Habitat.—South Pacific, Station 300, surface.

4. Saturnulus planetes, n. sp. (Pl. 16, fig. 17).

Cortical shell smooth, twice as broad as the medullary shell, with regular, circular pores, of the same breadth as the bars; sixteen to eighteen on the half equator. Ring elliptical, smooth, with strong prominent edges, constricted at the poles of the minor axis, its major diameter three times as great as that of the outer sphere.

Dimensions.—Diameter of the outer sphere 0.08, pores and bars 0.005; inner sphere 0.035; major axis of the ring 0.25, minor axis 0.2; thickness of the ring and the axial beams 0.012.

Habitat.—Indian Ocean, Sunda Strait, Rabbe; Station 200, surface.

Subfamily Amphistylida, Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.—Stylosphærida with three concentric spherical lattice-shells.

Genus 51. Amphisphæra, Haeckel,^[50] 1881, Prodromus, p. 452.

Definition.—Stylosphærida with three concentric lattice-spheres and two free spines of equal size and similar form.

The genus Amphisphæra differs from its probable ancestral form, Stylosphæra, in the triple spherical lattice-shell. Commonly two of these lie within the central capsule (medullary shell), whilst the third lies outside it (cortical shell). But sometimes this order is inverted, the cortical shell being double, the medullary shell simple; and perhaps these forms may better represent a peculiar genus, Amphisphæridium.

Subgenus 1. Amphisphærantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without spines or thorns.

1. Amphisphæra neptunus, n. sp.

Radial proportion of the three concentric spheres = 4 : 2 : 1. Cortical shell thick walled, smooth, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twelve to fifteen on the half equator. Polar spines three-sided pyramidal, with strong prominent edges, about as long as the radius of the outer shell, half as broad at the base. (Similar to Stylatractus neptunus, Pl. 17, fig. 6, but differs in the purely spherical form of the three concentric shells and the regular form of the network and of the polar spines.)

Dimensions.—Diameter of the outer shell 0.16, middle shell 0.08, inner shell 0.04; pores and bars of the cortical shell 0.008; length of the polar spines 0.08, basal breadth 0.04.

Habitat.—Pacific, central area, Station 271, depth 2425 fathoms.

2. Amphisphæra uranus, n. sp.

Radial proportion of the three spheres = 4 : 2 : 1. Cortical shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; ten to twelve on the half equator. Polar spines three-sided pyramidal, about as long as the diameter of the outer shell, twice as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.03; pores of the cortical shell 0.012, bars 0.004; length of the polar spines 0.1, basal breadth 0.024.

Habitat.—Western Indian Ocean, Zanzibar, 2200 fathoms, Pullen.

3. Amphisphæra jupiter, n. sp.

Radial proportion of the three spheres = 10 : 3 : 2. Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; twenty to twenty-five on the half equator. Polar spines cylindro-conical, nearly as long as the axis of the outer shell, twice as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.2, middle 0.06, inner 0.04; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.15 to 0.18, breadth 0.02.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Subgenus 2. Amphisphærella, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; surface thorny or spiny.

4. Amphisphæra apollo, n. sp.

Radial proportion of the three spheres = 3 : 1.5 : 1. Cortical shell thick walled, spiny, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twenty to twenty-two on the half equator. In each hexagon-corner (between three pores) a bristle-like radial spine. Polar spines cylindrical, with conical apex; one to one and a half times as long as the axis of the outer shell, as broad as three pores at the base. (Resembles closely Xiphosphæra pallas, Pl. 14, fig. 4, but differs in the presence of two medullary shells and the absence of the fine denticulations on the hexagonal crests.)

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.04; pores and bars of the cortical shell 0.006; length of the polar spines 0.15, breadth 0.02.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

5. Amphisphæra mercurius, n. sp.

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, spiny, with regular, circular pores, twice as broad as the bars; fifteen to eighteen on the half equator; between them short bristle-like radial spines. Polar spines three-sided pyramidal, about as long as the radius of the outer shell, one-third as broad at the base.

Dimensions.—Diameter of the outer shell 0.15, middle 0.09, inner 0.05; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.09, basal breadth 0.03.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

Subgenus 3. Amphisphærissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns.

6. Amphisphæra cronos, n. sp. (Pl. 17, fig. 5).

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, smooth, with irregular, roundish pores, two to four times as broad as the bars; eight to ten on the half equator. Outer medullary shell similar, but with pores of half the size, connected with the cortical shell by numerous radial beams; inner medullary shell with very small pores. Polar spines three-sided pyramidal, as long as the axis of the inner medullary shell, half as broad at the base.

Dimensions.—Diameter of the outer shell 0.12, middle 0.08, inner 0.04; pores of the cortical shell 0.01 to 0.02, bars 0.05; length of the polar spines 0.04, basal breadth 0.02.

Habitat.—South Atlantic, Station 330, surface.

7. Amphisphæra pluto, n. sp. (Pl. 17, figs. 7, 8).

Radial proportion of the three spheres about = 4 : 2 : 1 (or 11 : 7 : 3). Cortical shell thick walled, smooth, with very irregular, roundish pores, two to four times as broad as the bars; eight to ten on the half equator; often two to four pores confluent. Margin of their outer aperture double. Polar spines conical, double contoured, as long as the radius of the outer shell, one-third as broad at the base.

Dimensions.—Diameter of the outer shell 0.11, middle shell 0.07, inner shell 0.03; pores of the cortical shell 0.01 to 0.02, bars 0.06, length of the polar spines 0.06, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, surface.

Subgenus 4. Amphisphæromma, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

8. Amphisphæra mars, n. sp.

Radial proportion of the three spheres = 10 : 3 : 2. Cortical shell thin walled, thorny, with irregular, roundish pores, one to three times as broad as the bars; sixteen to twenty on the half equator. Irregularly scattered between them short conical thorns. Polar spines conical, about as long as the axis of the outer shell, as broad at the base as the inner shell.

Dimensions.—Diameter of the outer shell 0.2, middle shell 0.06, inner shell 0.04; pores of the cortical shell 0.005 to 0.02, bars 0.006; length of the polar spines 0.17, basal breadth 0.04.

Habitat.—North Atlantic, Gulf Stream, near Florida, depth 1500 fathoms, Schaffner.

Genus 52. Amphistylus,^[51] Haeckel, 1881, Prodromus, p. 452.

Definition.—Stylosphærida with three concentric lattice-spheres and two free spines of different size or form.

The genus Amphistylus differs from its ancestral form, Amphisphæra, by the differentiation of both polar spines, and exhibits therefore the same relation to it that Sphærostylus bears to Stylosphæra.

1. Amphistylus clio, n. sp.

Radial proportion of the three spheres = 4 : 2 : 1. Cortical shell thick walled, smooth; its pores regular, circular, three times as broad as the bars; eighteen to twenty on the half equator. Polar spines three-sided pyramidal, very stout, as broad at the base as the inner medullary shell; major spine somewhat longer than the diameter of the cortical shell; minor spine scarcely half as long. (Similar to Stylosphæra clio, Pl. 16, fig. 7, but different in the double medullary shell and the different length of the polar spines.)

Dimensions.—Diameter of the outer sphere 0.15, middle 0.08, inner 0.04; pores of the outer shell 0.01, bars 0.003; length of the major spine 0.17, minor 0.07, basal breadth 0.04.

Habitat.—Pacific, central area, Station 265, depth 2900 fathoms.

2. Amphistylus hippocampus, n. sp.

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thick walled, smooth; its pores regular, circular, hexagonally lobed, three times as broad as the bars; twelve to fifteen on the half equator. Major polar spine three-sided pyramidal, about as long as the axis of cortical shell; minor spine pommel-like, edged, scarcely one-third as long. (Similar to Sphærostylus hippocampus, Pl. 16, figs 10, 11, but differs in the larger size, the double medullary shell, and the straight, not curved, major spine.)

Dimensions.—Diameter of the outer sphere 0.11, middle 0.07, inner 0.035; pores of the outer shell 0.011, bars 0.004; length of the major spine 0.12, of the minor 0.04, breadth 0.03.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

3. Amphistylus glyptodon, n. sp.

Radial proportion of the three spheres = 6 : 3 : 1. Cortical shell thick walled, spiny, with irregular, roundish pores, two to four times as broad as the bars; ten to twelve on the half equator. Inner aperture of each pore closed by a thin fenestrated lamella with five to seven small pores. Major polar spine three-sided pyramidal, longer than the diameter of the outer sphere; minor polar spine scarcely as long as its radius, pommel-shaped. (Similar to Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but differs in the spherical, not ellipsoidal, form of the three shells and the size of the polar spines.)

Dimensions.—Diameter of the outer sphere 0.12, middle 0.06, inner 0.02; pores and spines of the outer shell 0.01 to 0.02, bars and porules 0.006; length of the major polar spine 0.15, of the minor 0.05, breadth 0.04.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

Genus 53. Saturninus,^[52] n. gen.

Definition.—Stylosphærida with three concentric lattice-spheres and two equal opposite spines, connected at the distal end by a circular or elliptical ring.

The genus Saturninus differs from the similar Saturnulus by the triplication of the spherical lattice-shell; the inner shell is enclosed in the central capsule, whilst both the others lie outside it.

1. Saturninus triplex, n. sp.

Radial proportion of the three spheres = 4 : 3 : 1. Inner cortical shell with regular, circular pores, of the same breadth as the bars, sixteen to eighteen on the half equator; outer cortical shell connected with the inner by numerous bristle-like radial spines, network very delicate, cobweb-shaped, with irregular polygonal meshes. Ring elliptical, two and a half times as broad as the outer shell.

Dimensions.—Diameter of the inner sphere 0.03, middle 0.09, outer 0.12; pores and bars of the middle shell 0.004; major axis of the elliptical ring 0.3, minor 0.25; thickness of the ring and the axial beams 0.008.

Habitat.—Central Pacific, Station 272, surface.

Subfamily Cromyostylida, Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Stylosphærida with four concentric spherical lattice-shells (two medullary and two cortical).

Genus 54. Stylocromyum,^[53] Haeckel, 1881, Prodromus, p. 453.

Definition.—Stylosphærida with four concentric lattice-spheres and two free spines of equal size and similar form.

The genus Stylocromyum differs from its probable ancestral form, Amphisphæra, by the duplication of the cortical shell; two opposite radial beams, piercing the wall of the central capsule, connect it with the double medullary shell, and are prolonged outside into two equal spines.

1. Stylocromyum amphiconus, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 1 : 2 : 8 : 9. Two medullary shells inside the central capsule, two cortical shells outside it. Interval between the second and third shells the greatest. Pores of all the shells regular, circular, two to four times as broad as the bars. Both polar spines equal, conical, about as long as the axis of the outermost sphere, as broad at the base as the innermost.

Dimensions.—Diameter of the four spheres—(A) inner medullary shell 0.03, (B) outer medullary shell 0.06, (C) inner cortical shell 0.25, (D) outer cortical shell 0.28; length of the polar spines 0.3, basal breadth 0.03.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

2. Stylocromyum amphipyramis, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 2 : 3 : 6 : 8. Both medullary shells with regular, circular pores, twice as broad as the bars. Both cortical shells with irregular, roundish, much larger pores, three to six times as broad as the bars. Both polar spines equal or nearly equal, three-sided pyramidal, about as long as the axis of the third shell.

Dimensions.—Diameter of the four spheres—(A) 0.04, (B) 0.06, (C) 0.12, (D) 0.16; length of the polar spines 0.11, basal breadth 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 55. Cromyostylus,^[54] Haeckel, 1881, Prodromus, p. 453.

Definition.—Stylosphærida with four concentric lattice-spheres and two free spines of different size or form.

The genus Cromyostylus differs from its ancestral form, Stylocromyum, in the differentiation of the two unequal polar spines.

1. Cromyostylus gladius, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 1 : 3 : 10 : 12. Both medullary shells with regular, circular, simple pores. Inner cortical shell with regular, circular, hexagonally framed pores, twice as broad as the bars. From each hexagon-corner arises a bristle-shaped radial spine, which at the distal end gives off three thread-like branches; by communication of these threads (at equal distances from the centre) the delicate outer medullary shell is formed. The polar spines very different; major spine six-sided pyramidal, longer than the diameter of the shell; minor pommel-shaped, shorter than the radius (similar to Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but different in the double spherical cortical shell).

Dimensions.—Diameter of the four spheres—(A) 0.02, (B) 0.06, (C) 0.2, (D) 0.24; length of the major spine 0.3, of the minor 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily Caryostylida, Haeckel, 1881, Prodromus, pp. 449, 454.

Definition.—Stylosphærida with five or more concentric, spherical lattice-shells.

Genus 56. Caryostylus, Haeckel, 1881, Prodromus, p. 454.

Definition.—Stylosphærida with five to six or more concentric lattice-shells and two free opposite spines of equal size and similar form.

The genus Caryostylus differs from its ancestral form, Stylocromyum, by the multiplication of the concentric spheres, the number of which amounts to five or six or more. I have only observed one single species of this genus. Some similar forms which in my Prodromus (1881, p. 454) were annexed to it, and disposed in three nearly allied genera (Caryoxiphus, Caryodoras, Caryolonche), have now been proved to belong to other groups, mainly ellipsoidal Druppulida.

1. Caryostylus hexalepas, n. sp.

Surface of the spherical shell smooth. Radial proportion of the component six concentric shells = 1 : 2 : 7 : 9 : 12 : 15. Both medullary shells connected only by six radial beams, opposite in pairs in the three dimensive axes. Between second and third shell numerous (twenty regularly disposed?) radial beams. Four cortical shells connected by very numerous (sixty to eighty or more?) short radial beams. Pores of all six shells regular, circular, the size increasing towards the surface, two to three times as broad as the bars. Two opposite polar spines very large, of equal size, three times as long as the shell radius, cylindrical, club-shaped at the thicker distal end. (The whole shell structure is similar to Pl. 15, fig. 2, but the shells are spherical, not ellipsoidal.)

Dimensions.—Diameter of the six spheres—(A) 0.02, (B) 0.04, (C) 0.15, (D) 0.18, (E) 0.24, (F) 0.3; length of the spines 0.5.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

Subfamily Spongostylida, Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.—Stylosphærida with spherical spongy shell (with or without enclosed latticed medullary shells).

Genus 57. Spongolonchis,^[55] Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with a solid sphere of spongy framework, and with two opposite free radial spines.

The genus Spongolonchis differs from its probable ancestral form, Styptosphæra, by the development of two opposite radial spines situated in one axis.

1. Spongolonchis compacta, n. sp.

Spongy framework of the spherical shell very compact, with small meshes, three to four times as broad as the bars. Surface rough, but not spiny. Two polar spines pyramidal, only as long as the radius of the shell, one-third as broad at the base.

Dimensions.—Diameter of the shell 0.2; length of the spines 0.1, basal breadth 0.03.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Spongolonchis laxa, n. sp.

Spongy framework loose, with large meshes, ten to twelve times as broad as the bars. Surface spiny. Two polar spines three-sided prismatic, longer than the diameter of the shell (broken off in the observed specimen).

Dimensions.—Diameter of the shell 0.5; length of the spine 0.6 and more, breadth 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 58. Spongostylus,^[56] Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with spongy spherical cortical shell, enclosing in the centre a simple latticed medullary shell, and with two opposite free radial spines.

The genus Spongostylus may probably be derived from Spongoplegma by development of two opposite radial spines in one axis.

1. Spongostylus hastatus, n. sp.

Spongy cortical shell with compact framework, twice as broad as the enclosed medullary shell, the pores of which are regular, circular, twice as broad as the bars. Two polar spines, three times as long as the radius of the shell, in the basal two-thirds cylindrical, in the distal third compressed, two-edged, spear-shaped.

Dimensions.—Diameter of the cortical shell 0.1, medullary shell 0.05; length of the spines 0.15.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

2. Spongostylus gladiatus, Haeckel.

Stylosphæra holosphæra, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 14.

Spongy cortical shell with rather compact framework, four times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, three to four times as broad as the bars. Two polar spines sword-shaped, two-edged, as long as the shell diameter.

Dimensions.—Diameter of the cortical shell 0.24, medullary shell 0.06; length of the spines 0.25.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; Philippine Sea, depth 3300 fathoms.

3. Spongostylus serratus, n. sp.

Spongy cortical shell with lax framework, ten to twelve times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, once and a half to twice as broad as the bars. Two polar spines longer than the shell diameter (broken off in the observed specimen), three-sided prismatical, with three straight serrated edges.

Dimensions.—Diameter of the cortical shell 0.5, medullary shell 0.04; length of the spines 0.6 or more.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

Genus 59. Spongostylidium,^[57] Haeckel, 1881, Prodromus, p. 455.

Definition.—Stylosphærida with spongy spherical cortical shell, enclosing two concentric spherical latticed medullary shells, and with two opposite, free radial spines.

The genus Spongostylidium differs from Spongostylus by duplication of the latticed medullary shell, and therefore bears the same relation to it as Spongodictyon to Spongoplegma.

1. Spongostylidium streptacanthum, n. sp.

Both medullary shells spherical, with small, regular, circular pores, twice as broad as the bars (outer twice as broad as the inner). Spongy cortical shell enclosing it with dense framework, four times as broad as the outer medullary shell. Two polar spines very large, four times as long as the diameter of the outer shell; as broad as the inner medullary shell, with three dentated, spirally contorted edges. (Very similar to the common Spongosphæra streptacantha and to Hexadoridium streptacanthum, but with only two opposite spines in one axis.)

Dimensions.—Diameter of the cortical shell 0.16, of the outer medullary shell 0.04, inner 0.02; length of the spines 0.7 and more, breadth 0.02.

Habitat.—Indian Ocean, Cocos Islands, Rabbe.

Family VIII. Staurosphærida, Haeckel (Pl. 15).

Staurosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with four radial spines on the surface of the spherical shell, forming a regular cross, being opposite in pairs in two axes perpendicular to one another; living solitary (not associated in colonies).

The family Staurosphærida is distinguished from the other Sphæroidea by the possession of four radial spines, which are opposite in pairs in two perpendicularly crossed axes. By these "two main axes" an equatorial plane is determined, which approximates them to the Discoidea. But in the latter the shells as well as the central capsule become more or less flattened, lenticular, or discoidal, whilst in the former they remain spherical. However, some forms of both groups are very similar, and inspection from different sides (and mainly from the margin of the equatorial plane) is required to determine the spherical (not compressed) shell-form of the Staurosphærida. As a rule the species of this family are much rarer, and much less numerous, than those of all the other Sphæroidea.

The most simple Staurosphærida are the Staurostylida, with one single spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Staurosphærida concentrica," since their carapace is composed of two or more concentric lattice-shells; two in the Staurolonchida, three in the Stauracontida, four in the Staurocromyida, five or more in the Staurocaryida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated spheres. In a sixth subfamily, in the Staurodorida, the shell is wholly or partially composed of irregular spongy wickerwork, with or without a medullary shell in the centre.

The Four Radial Spines in all Staurosphærida are normally opposed in pairs in two axes perpendicular one to another, and therefore together form a rectangular cross. But in many species besides this normal form individual abnormalities occur, in which the four spines in the equatorial plane are not quite accurately opposed, so that the four angles between them are not right angles, but more or less unequal. More rarely also their position in the equatorial plane is not accurately retained, so that they are placed in two, three, or four different meridian planes, intersecting at very small variable angles.

In the greater part of Staurosphærida all four radial spines are quite equal, and of the same size and form. But in some genera there takes place a more or less considerable differentiation of the four spines, commonly in pairs, so that the two opposite spines of each pair are equal, but the pairs different (Staurostylus, Staurolonchidium). More rarely also both spines of one pair become unequal, whilst those of the other pair remain equal (Stauroxiphos). Very rarely all four spines assume a different size or form.

Synopsis of the Genera of Staurosphærida.

I. Subfamily Staurostylida. (Shell one single lattice-sphere.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	All four spines equal,			60. Staurosphæra.
		Four spines different in pairs,			61. Staurostylus.
		One spine larger than the three others,			62. Stylostaurus.
II. Subfamily Staurolonchida. (Shell with two concentric lattice-spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	All four spines equal,	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Simple,	63. Staurolonche.
				Branched,	64. Staurancistra.
		Four spines different in pairs,			65. Staurolonchidium.
		One spine larger than the three others,			66. Stauroxiphos.
III. Subfamily Stauracontida. (Shell with three concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	All four spines equal, simple,			67. Stauracontium.
IV. Subfamily Staurocromyida. (Shell with four concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	All four spines equal,	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Simple,	68. Staurocromyum.
				Branched,	69. Cromyostaurus.
V. Subfamily Staurocaryida. (Shell with five or more concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	All four spines equal,			70. Staurocaryum.
VI. Subfamily Staurodorida. (Shell a spongy sphere.)	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Solid spongy sphere without medullary shell,			71. Staurodoras.

Subfamily Staurostylida,^[58] Haeckel, Prodromus, 1881, pp. 449, 450.

Definition.—Staurosphærida with one single spherical lattice-shell.

Genus 60. Staurosphæra,^[59] Haeckel, 1881, Prodromus, p. 450.

Definition.—Staurosphærida with a single lattice-sphere and four crossed equal spines.

The genus Staurosphæra may be regarded as the common ancestral form of this subfamily, since it represents their most simple and primitive form. From the surface of the simple lattice-sphere, enclosing the central capsule, arise four equal, simple, radial spines, opposite in pairs in two diameters, perpendicular one to another. Staurosphæra may be derived phylogenetically either from Cenosphæra by production of the four spines, or from Hexastylus by reduction of two opposite spines.

Subgenus 1. Staurosphærantha, Haeckel.

Definition.—Pores regular, all of nearly equal size and similar form; surface smooth.

1. Staurosphæra cruciata, n. sp.

Shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; ten to twelve on the quadrant. Four crossed radial spines three-sided pyramidal, as long as the diameter of the shell, as broad at the base as one pore (very similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but with only four spines).

Dimensions.—Diameter of the shell 0.12, of the pores 0.008, bars 0.002.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Staurosphæra christiana, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, three times as broad as the bars; six to eight on the quadrant. Four crossed spines six-sided pyramidal, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.13, pores 0.012, bars 0.004.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Staurosphæra johannis, n. sp.

Shell thick walled, smooth, with regular, circular pores, four times as broad as the bars; five to six on the quadrant. Four spines six-sided pyramidal, half as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.15, pores 0.02, bars 0.005.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Staurosphæra pauli, n. sp.

Shell very thick walled, smooth, with regular, circular, double-edged pores, four times as broad as the bars; eight to ten on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.15, pores 0.016, bars 0.004.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

5. Staurosphæra petri, n. sp.

Shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; twenty to twenty-two on the quadrant. Four spines conical, half as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.22, pores 0.006, bars 0.002.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms; also fossil in Barbados.

6. Staurosphæra jacobi, n. sp.

Shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; eleven to twelve on the quadrant. Four spines cylindrical, three times as long as the radius, three times as broad as one mesh.

Dimensions.—Diameter of the shell 0.1, pores 0.006, bars 0.003.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

7. Staurosphæra simonis, n. sp.

Haliomma with four spines, Bury, 1862, Polycystins of Barbados, pl. iv. fig. 4.

Shell thick walled, smooth, with regular, circular pores, of the same breadth as the bars; eight to ten on the quadrant. Four spines cylindrical, twice as long as the radius, five times as broad as one mesh.

Dimensions.—Diameter of the sphere 0.1, pores and bars 0.003.

Habitat.—Fossil in Barbados.

Subgenus 2. Staurosphærella, Haeckel.

Definition.—Pores regular, all of nearly equal size and similar form; surface covered with by-spines or accessory thorns.

8. Staurosphæra philippi, n. sp. (Pl. 15, fig. 6).

Shell thin walled, covered with bristle-shaped by-spines, as long as the radius. Pores regular, circular, twice as broad as the bars; six to eight on the quadrant. Four main spines cylindrical, five to ten times as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the shell 0.08, pores 0.006, bars 0.003.

Habitat.—Central Pacific, Station 272, surface.

9. Staurosphæra andreæ, n. sp.

Shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars; nine to ten on the quadrant. From each hexagon-corner arises a bristle-shaped by-spine, half as long as the radius. Four main spines three-sided pyramidal, with spirally contorted edges, as long as the radius (very similar to Hexastylus solonis, Pl. 21, fig. 11, but with only four spines).

Dimensions.—Diameter of the shell 0.16, pores 0.01, bars 0.003.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

10. Staurosphæra thomæ.

Shell thick walled, with regular, circular pores, twice as broad as the bars; twelve to fourteen on the quadrant; surface covered with short conical by-spines. Four main spines conical, twice as long as the radius, twice as broad as one mesh.

Dimensions.—Diameter of the sphere 0.2, pores 0.012, bars 0.006.

Habitat.—South Atlantic, Station 332, depth, 2200 fathoms.

Subgenus 3. Staurosphærissa, Haeckel.

Definition.—Pores irregular, of different size or form; surface smooth.

11. Staurosphæra judæ, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores, twice to four times as broad as the bars; six to ten on the quadrant. Four main spines three-sided pyramidal, as long as the radius.

Dimensions.—Diameter of the sphere 0.15, pores 0.006 to 0.012, bars 0.003.

Habitat.—Central Pacific, Station 273, depth, 2350 fathoms.

12. Staurosphæra crassa, Dunikowski.

Staurosphæra crassa, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 27, Taf. v. figs. 52-55.

Shell thick walled, smooth, with irregular, roundish pores, scarcely broader than the bars; eight to ten on the quadrant. Four spines three-sided pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the sphere 0.19, pores and bars 0.015.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg, Dunikowski).

13. Staurosphæra apostolorum, Haeckel.

? Cenosphæra megapora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iii. fig. 1. ? Cenosphæra micropora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iii. fig. 2.

Shell thin walled, smooth, with large, irregular, roundish pores, twice to six times as broad as the bars; four to six on the quadrant. Four spines conical, very stout, about as long as the shell diameter, often more or less irregularly disposed.

Dimensions.—Diameter of the sphere 0.12 to 0.2, pores 0.01 to 0.03, bars 0.005.

Habitat.—Fossil in Barbados.

Subgenus 4. Staurosphæromma, Haeckel.

Definition.—Pores irregular, of different size or form; surface covered with by-spines or accessory thorns.

14. Staurosphæra bartholomæi, n. sp.

Shell thin walled, with irregular, polygonal pores, three times as broad as the bars; six to eight on the quadrant; surface covered with short bristle-shaped by-spines. Four main spines three-sided pyramidal, twice as long as the radius.

Dimensions.—Diameter of the shell 0.14, pores 0.008 to 0.016, bars 0.003 to 0.005.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

15. Staurosphæra thaddæi, n. sp.

Shell thick walled, with irregular, roundish, polygonally framed pores, twice to three times as broad as the bars; five to seven on the quadrant; surface covered with bristle-shaped spines, half as long as the radius. Four main spines pyramidal, as long as the radius.

Dimensions.—Diameter of the shell 0.12, pores 006 to 0.012, bars 0.004.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.

16. Staurosphæra matthæi, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the quadrant; surface covered with short conical thorns or by-spines. Four main spines conical, as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores 0.004 to 0.01, bars 0.002.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Genus 61. Staurostylus,^[60] Haeckel, 1881, Prodromus, p. 450.

Definition.—Staurosphærida with one single lattice-sphere and four crossed spines which are arranged in opposite pairs, one pair opposite being larger than the other.

The genus Staurostylus has been developed from Staurosphæra by differentiation of the four crossed spines in pairs; two opposite spines growing much more strongly than the other two.

1. Staurostylus græcus, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; six to eight on the quadrant. Spines three-sided prismatic, pointed, as broad as one mesh; two opposite larger spines as long as the diameter of the shell, two smaller only as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores 0.01, bars 0.005; length of the major spines 0.16, minor 0.08.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Staurostylus latinus, n. sp.

Shell thin walled, smooth, with regular, circular, double-edged pores, three times as broad as the bars; twelve to fourteen on the quadrant. Spines conical, twice as broad at the base as one mesh; two opposite larger spines as long as the radius of the shell, two smaller only one-third as long.

Dimensions.—Diameter of the shell 0.24, pores 0.012, bars 0.004; length of the major spines 0.12, minor 0.04.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

3. Staurostylus germanicus, n. sp.

Shell thick walled, covered with bristle-shaped by-spines, half as long as the radius. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. From each hexagon-corner arises one short by-spine. Four main spines three-sided pyramidal, as broad at the base as one mesh; two opposite larger spines one and a half times as long as the radius, two smaller two-thirds as long.

Dimensions.—Diameter of the shell 0.16, pores 0.008, bars 0.004; length of the major spines 0.12, minor 0.08.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

Genus 62. Stylostaurus,^[61] 1881, Prodromus, p. 450.

Definition.—Staurosphærida with one single lattice-sphere and four crossed spines, one of which is much larger than the other three.

The genus Stylostaurus differs from the preceding in the extraordinary development of one of the four spines, which is much longer than the other three; these may be equal or different.

1. Stylostaurus caudatus, n. sp. (Pl. 13, fig. 7).

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; five to six on the quadrant. Spines three-sided pyramidal, as broad at the base as one mesh; one of the spines longer than the shell diameter, the opposite spine nearly as long as the shell radius; both lateral spines scarcely one-third as long.

Dimensions.—Diameter of the shell 0.1, pores 0.01, bars 0.005; length of the major spine 0.14, of the opposite 0.04, of both lateral spines 0.012.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Stylostaurus gladiatus, n. sp.

Shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; nine to ten on the quadrant. Spines three-sided prismatic, as broad at the base as one mesh; one of the spines longer than the shell diameter, and much larger than the other three, which are nearly equal (half as long as the radius).

Dimensions.—Diameter of the shell 0.2, pores 0.015, bars 0.005; length of the major spine 0.25, of the three others 0.005.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily Staurolonchida,^[62] Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Staurosphærida with two concentric spherical lattice-shells.

Genus 63. Staurolonche,^[63] Haeckel, 1881, Prodromus, p. 451.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurolonche may be derived either from Staurosphæra by the duplication of the lattice-sphere, or from Carposphæra by the production of four crossed radial spines, lying in one meridional plane, or from Hexalonche by the reduction of two opposite spines.

Subgenus 1. Staurolonchantha, Haeckel.

Definition.—Pores of the cortical shell regular, and of nearly equal size and similar form; surface smooth.

1. Staurolonche hexagona, n. sp.

Haliomma hexagonum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvb., Bd. iv. fig. 17. Haliomma hexagonum, Haeckel, 1862, Monogr. d. Radiol., p. 434.

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, hexagonal pores, four times as broad as the bars; seven to eight on the quadrant. Four spines three-sided pyramidal, somewhat longer than the radius, as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.012, bars 0.003; length of the spines 0.08.

Habitat.—North Atlantic, Station 64, depth 2700 fathoms.

2. Staurolonche spinozæ, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell, with regular, circular, hexagonally framed pores, three times as broad as the bars; five to six on the quadrant. Four spines three-sided pyramidal, half as long as the radius, as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.16, inner 0.08; cortical pores 0.012, bars 0.004; length of the spines 0.04.

Habitat.—Central Pacific, Station 271, surface.

3. Staurolonche aperta, Haeckel.

Haliomma apertum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxviii. fig. 5.

Cortical shell thin walled, smooth, three times as broad as the medullary shell; pores regular, circular, five times as broad as the bars; four to five on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.1, inner 0.03; cortical pores 0.015, bars 0.003; length of the spines 0.05.

Habitat.—Fossil in Barbados.

4. Staurolonche brunonis, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; eight to ten on the quadrant. Four spines cylindro-conical, longer than the diameter, twice as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.08, inner 0.04; cortical pores 0.006, bars 0.002; length of the spines 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Staurolonche pertusa, n. sp. (Pl. 15, figs. 5, 5a).

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; eight to ten on the quadrant. Pores of the medullary shell only one-third as large, also circular. Four spines three-sided prismatic, three times as long as the radius; each of their three thin wings perforated by a single row of small pores.

Dimensions.—Diameter of the outer shell 0.1, inner 0.033; cortical pores 0.01, bars 0.003; length of the spines 0.15.

Habitat.—North Atlantic, Station 353, surface.

Subgenus 2. Staurolonchella, Haeckel.

Definition.—Pores of the cortical shell regular, and of nearly equal size and similar form; surface covered with by-spines or thorns.

6. Staurolonche straussii, n. sp.

Cortical shell thin walled, four times as broad as the medullary shell, and covered with numerous bristle-shaped by-spines, half as long as the radius. Pores regular, circular, hexagonally framed, twice as broad as the bars; six to eight on the radius. On each hexagonal frame twelve by-spines (six at the corners, six in the middle between them). Four main spines six-sided pyramidal, about as long as the radius, twice as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.16, inner 0.04; cortical pores 0.016, bars 0.008; length of the spines 0.1.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

7. Staurolonche feuerbachii, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with short conical by-spines. Pores regular, circular, twice as broad as the bars; twenty to twenty-two on the quadrant. Four main spines three-sided prismatic, with pyramidal apex, two to three times as long as the radius, twice as broad as one mesh.

Dimensions.—Diameter of the outer shell 0.27, of the inner 0.055; cortical pores 0.008, bars 0.004; length of the spines 0.3 to 0.4.

Habitat.—Fossil in Barbados.

8. Staurolonche moleschottii, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, and covered with short conical by-spines. Pores regular, circular, of the same breadth as the bars; fourteen to sixteen on the quadrant. Four main spines conical, as long as the radius, three times as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; cortical pores and bars 0.004; length of the spines 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subgenus 3. Staurolonchissa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth.

9. Staurolonche holbachii, n. sp.

Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores irregular, polygonal, twice to four times as broad as the bars. Four main spines three-sided prismatic, longer than the shell diameter.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.15.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

10. Staurolonche gassendii, n. sp.

Cortical shell thick walled, with smooth surface, four times as broad as the medullary shell. Pores irregular, roundish, three to five times as broad as the bars. Four main spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.2, inner 0.05; cortical pores 0.01 to 0.02, bars 0.004; length of the spines 0.1.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

Subgenus 4. Staurolonchura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface covered with by-spines or thorns.

11. Staurolonche epicurii, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with numerous bristle-shaped by-spines (half as long as the radius). Pores irregular, roundish, polygonally framed, twice to three times as broad as the bars. Four main spines pyramidal, as long as the radius.

Dimensions.—Diameter of the outer shell 0.22, inner 0.044; cortical pores 0.02 to 0.04, bars 0.012; length of the spines 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

12. Staurolonche lucretii, n. sp.

Cortical shell thick-walled, three times as broad as the medullary shell, and covered with numerous short, conical thorns. Pores irregular, roundish, twice to four times as broad as the bars. Four main spines conical, half as long as the radius.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; cortical pores 0.015 to 0.03, bars 0.008; length of the spines 0.04.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 64. Staurancistra,^[64] Haeckel, 1881, Prodromus, p. 451.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed, equal, branched spines.

The genus Staurancistra differs from its ancestral form, Staurolonche, in the ramification of the four crossed spines.

1. Staurancistra quadricuspis, n. sp.

Cortical shell thin walled, with rough, thorny surface, and irregular, roundish pores, twice to four times as broad as the bars; six to eight on the quadrant. Medullary shell one-third as large, with regular, circular pores; connected with the cortical shell by four crossed radial beams. These are prolonged outside into four strong three-sided prismatic spines, nearly as long as the shell diameter, each having three curved branches below the distal end. (Similar to Hexancistra quadricuspis, Pl. 22, fig. 11, but with only four spines.)

Dimensions.—Diameter of the cortical shell 0.16, of the medullary shell 0.05; pores of the former 0.06 to 0.012, bars 0.003; length of the spines 0.14, breadth 0.012.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 65. Staurolonchidium,^[65] n. gen.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed simple spines which are disposed in two different pairs, two opposite being larger than the other two.

The genus Staurolonchidium has arisen from Staurolonche by the stronger growth of the two opposite spines, the other two remaining stationary; both spines of each pair equal.

1. Staurolonchidium artioscelides, n. sp.

Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. Four radial spines three-sided pyramidal, as broad as one mesh; two opposite larger spines three times as long as the two smaller, which are about equal to the radius.

Dimensions.—Diameter of the cortical shell 0.16, medullary shell 0.05; pores of the former 0.012, bars 0.006; length of the major spines 0.24, minor 0.08.

Habitat.—Central Pacific, Station 265, surface.

2. Staurolonchidium perspicuum, Haeckel.

Haliomma perspicuum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxix. fig. 1.

Cortical shell thin walled, covered with small conical by-spines, five times as broad as the medullary shell. Pores regular, circular, eight times as broad as the bars; three to four on the quadrant. Four radial spines three-sided pyramidal, scarcely one-third as broad as one mesh; two opposite larger spines four times as long as the two smaller, which are about equal to half the radius.

Dimensions.—Diameter of the cortical shell 0.12, medullary shell 0.025; pores of the former 0.03, bars 0.004; length of the major spines 0.12, minor 0.03.

Habitat.—Fossil in Barbados.

Genus 66. Stauroxiphos,^[66] n. gen.

Definition.—Staurosphærida with two concentric lattice-spheres and four crossed simple spines, one of which is much larger than the other three.

The genus Stauroxiphos differs from its ancestral form, Staurolonche, in the greater development of one single spine, and exhibits therefore the same relation to it that Stylostaurus bears to Staurosphæra.

1. Stauroxiphos gladius, n. sp. (Pl. 15, fig. 7).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores of the outer shell regular, circular, regularly six-lobed on the outer opening, four times as broad as the bars; about six on the quadrant. Pores of the inner shell only one-third as large, simple, circular. Three of the four radial spines of nearly equal size, pommel-shaped, with three prominent, dentated wings, somewhat shorter than the shell radius and about half as broad as long; the fourth spine much larger, sword-like, about three times as long as the shell radius.

Dimensions.—Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.01, bars 0.0025; pores of the latter 0.003, bars 0.001; length of the major spine 0.18, of the three minor 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subfamily Stauracontida,^[67] Haeckel, 1881, Prodromus, p. 52.

Definition.—Staurosphærida with three concentric spherical lattice-shells.

Genus 67. Stauracontium,^[68] Haeckel, 1881, Prodromus, p. 452.

Definition.—Staurosphærida with three concentric lattice-spheres and four crossed, equal, simple spines.

The genus Stauracontium differs from its probable ancestral form, Staurolonche, in the duplication of the cortical shell.

Subgenus 1. Stauracontarium, Haeckel.

Definition.—Pores of the cortical shell regular, all of nearly equal size and similar form; surface smooth.

1. Stauracontium cruciferum, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; eight to ten on the quadrant. Radial proportion of the three spheres = 1 : 3 : 9. Connecting radial beams between them six (opposite in pairs in the three dimensive axes), but only four of them are prolonged outside into four stout three-sided prismatic spines, lying in one equatorial plane, as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.22, middle 0.07, inner 0.025; cortical pores 0.012, bars 0.003; length of the spines 0.2.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Stauracontium tetracanthum, Haeckel.

Haliomma tetracanthum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. x. figs. 7, 8.

Cortical shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; five to six on the quadrant. Radial proportion of the three spheres = 1 : 3 : 12. Radial spines three-sided pyramidal, about as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.12, middle 0.03, inner 0.01; cortical pores 0.01, bars 0.003; length of the spines 0.1.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms, Pullen.

3. Stauracontium tetracontium, Haeckel.

Actinomma tetracanthum, Stöhr, 1880, Palæontogr. 26, p. 91, Taf. ii. fig. 6.

Cortical shell thin walled, rough, with regular, circular pores, of the same breadth as the bars; six to seven on the quadrant. Radial proportion of the three spheres = 1 : 2.5 : 8. Radial spines three-sided pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.1, middle 0.03, inner 0.013; cortical pores and bars 0.006; length of the spines 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

Subgenus 2. Stauracontellium, Haeckel.

Definition.—Pores of the cortical shell regular, and of nearly equal size and similar form; surface covered with numerous small thorns or by-spines.

4. Stauracontium daturæforme, Haeckel.

Actinomma daturæforme, Stöhr, 1880, Palæontogr. 26, p. 93, Taf. ii. fig. 13.

Cortical shell thick walled, covered with short thorns, and with regular, hexagonal pores, five times as broad as the bars; six to seven on the quadrant. Radial proportion of the three spheres = 1 : 3 : 3.5. Radial spines six-sided pyramidal, about half as long as the radius and one-fourth as broad.

Dimensions.—Diameter of the outer shell 0.15, middle 0.13, inner 0.04; cortical pores 0.017, bars 0.003; length of the spines 0.03.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Stöhr.

5. Stauracontium sparganium, n. sp.

Cortical shell thick walled, covered with very numerous, short, conical spines, and with regular, circular pores, five times as broad as the bars; sixteen to eighteen on the quadrant. Radial proportion of the three spheres = 2 : 3 : 9. Radial main spines three-sided prismatic, as long as the radius or longer.

Dimensions.—Diameter of the outer shell 0.275, middle 0.09, inner 0.06; cortical pores 0.01, bars 0.002; length of the spines 0.15.

Habitat.—Fossil in Barbados.

Subgenus 3. Stauracontidium, Haeckel.

Definition.—Pores irregular, of different size or form; surface smooth.

6. Stauracontium antarcticum, n. sp.

Cortical shell thin walled, smooth. Pores irregular, roundish, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 8. Radial spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.025; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Stauracontonium, Haeckel.

Definition.—Pores irregular, of different size or form; surface covered with thorns or by-spines.

7. Stauracontium setosum, n. sp.

Cortical shell thin walled, covered with thin bristle-shaped by-spines, half as long as the radius. Pores irregular, polygonal, three to five times as broad as the bars. Proportion of the three spheres = 1 : 2 : 6. Radial main spines pyramidal, nearly as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.15, middle 0.05, inner 0.025; cortical pores 0.01 to 0.015, bars 0.003; length of the spines 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

8. Stauracontium papillosum, n. sp.

Cortical shell thick walled, covered with short conical papillæ or by-spines. Pores irregular, roundish, two to four times as broad as the bars. Proportion of the three spheres = 1 : 3 : 12. Radial main spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.24, middle 0.06, inner 0.02; cortical pores 0.007 to 0.015, bars 0.004; length of the spines 0.12.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subfamily Staurocromyida,^[69] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Staurosphærida with four concentric spherical lattice-shells.

Genus 68. Staurocromyum,^[70] Haeckel, 1881, Prodromus, p. 453.

Definition.—Staurosphærida with four concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurocromyum has arisen probably from Stauracontium by duplication of the cortical shell, two concentric shells lying within, two others outside the central capsule.

1. Staurocromyum quadruplex, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Both medullary shells with very small, regular, circular pores. Inner cortical shell with regular, circular, hexagonally-framed pores, twice as broad as the bars; from each hexagon-corner arises a small by-spine, and these, connected by tangential branches at equal distances from the centre, form the delicate outer cortical shell, with spiny surface. Four main spines three-sided pyramidal, as long as the shell radius.

Dimensions.—Diameter of the four shells—(A) 0.25, (B) 0.2, (C) 0.05, (D) 0.025; length of the spines 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Staurocromyum quadrispinum, n. sp.

Radial proportion of the four spheres = 1 : 3 : 9 : 12. Both medullary shells with small, regular, circular pores. Both cortical shells with irregular, roundish pores. Surface covered with short, conical by-spines. Four main spines cylindro-conical, somewhat longer than the shell diameter.

Dimensions.—Diameter of the four shells—(A) 0.24, (B) 0.18, (C) 0.06, (D) 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 69. Cromyostaurus,^[71] Haeckel, 1881, Prodromus, p. 453.

Definition.—Staurosphærida with four concentric lattice-spheres and four crossed, equal, branched spines.

The genus Cromyostaurus differs from the preceding Staurocromyum, its ancestral form, in the ramification of the four crossed spines.

1. Cromyostaurus verticillatus, n. sp.

Radial proportion of the four spheres = 1 : 3 : 11 : 13. Both medullary shells with small, regular, circular pores; inner cortical shell with regular, hexagonal pores; from the hexagon-corners arise small, radial by-spines, which at equal distances from the centre send out forked tangential branches, three from each spine, and by communication of these form the outer, delicate, cortical shell. Four main spines nearly as long as the shell diameter, three-sided prismatic, with four to six verticils of ramified lateral branches, each verticil composed of three forked branches, which ramify again.

Dimensions.—Diameter of the four shells—(A) 0.26, (B) 0.22, (C) 0.06, (D) 0.02; length of the spines 0.24.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subfamily Staurocaryida,^[72] Haeckel, 1881, Prodromus, pp. 449, 454.

Definition.—Staurosphærida with five or more concentric spherical lattice-shells.

Genus 70. Staurocaryum,^[73] Haeckel, 1881, Prodromus, p. 454.

Definition.—Staurosphærida with five or more concentric lattice-spheres and four crossed, equal spines.

The genus Staurocaryum has arisen from the preceding Staurocromyum by the further multiplication of the concentric spheres; in the only observed form there are six, at nearly equal distances apart.

1. Staurocaryum arborescens, n. sp. (Pl. 15, fig. 8).

Shell composed of six concentric latticed spheres, at nearly equal distances apart, and with somewhat regular, circular pores, the size of which gradually increases from the first to the sixth shell. The surface of the outermost shell is densely covered with numerous arborescent by-spines, which bifurcate from three to four times, and are three-sided pyramidal at the base, and twice as long as the distance between each two shells. The six shells are connected only by four crossed, conical, radial beams, which increase in diameter from the centre, and are prolonged outside into very stout cylindrical, radial spines, irregularly covered with small thorns and forked ramules, and nearly as long as the shell diameter. Only a single specimen was observed.

Dimensions.—Diameter of the whole shell 0.22; distance between each two shells 0.02; length of the by-spines 0.05, of the main spines 0.2.

Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.

Subfamily Staurodorida,^[74] Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.—Staurosphærida with spongy, spherical shell (with or without enclosed concentric lattice-shells).

Genus 71. Staurodoras,^[75] Haeckel, 1881, Prodromus, p. 455.

Definition.—Staurosphærida with solid, spongy, spherical shell and four crossed simple spines.

The genus Staurodoras may be developed from Styptosphæra by the production of four crossed spines on the simple, spongy, spherical shell, which is composed of looser or denser irregular wicker-work, without enclosed medullary shell.

1. Staurodoras spongosphæra, n. sp.

Four crossed spines, two to three times as long as the diameter of the spongy sphere, three-sided prismatic, with three dentated and spirally contorted edges. (Form of Spongosphæra streptacantha, but without medullary shell and with four equal spines, crossed regularly at right angles.)

Dimensions.—Diameter of the sphere 0.25; length of the spines 0.4 to 0.7.

Habitat.—Central Pacific, Station 271, surface.

2. Staurodoras mojsisovicsi, Dunikowski.

Staurodoras mojsisovicsi, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 56.

Four crossed spines, one and a half times as long as the diameter of the spongy sphere, three-sided pyramidal, with three smooth edges. (What Dunikowski describes as "inner canals" of the spines are their edges.)

Dimensions.—Diameter of the sphere 0.14; length of the spines 0.18 to 0.2. basal breadth 0.04.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg).

3. Staurodoras liassica, Dunikowski.

Staurodoras liassica, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 57.

Four crossed spines, shorter than the diameter of the spongy sphere, conical or pyramidal (?).

Dimensions.—Diameter of the sphere 0.19; length of the spine 0.13, basal breadth 0.045.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg).

4. Staurodoras wandae, Dunikowski.

Staurodoras wandae, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 58.

Four crossed spines shorter than the radius of the spongy sphere, conical. (May be the young form of the preceding species.)

Dimensions.—Diameter of the sphere 0.14; length of the spines 0.06, basal breadth 0.05.

Habitat.—Fossil in the Alpine Lias (Schafberg near Salzburg).

Family IX. Cubosphærida, Haeckel (Pls. 21-25).

Cubosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with six radial spines on the surface of the spherical shell, opposite in pairs in the three dimensive axes, perpendicular one to another; living solitary (not associated in colonies).

The family Cubosphærida is distinguished from the other Sphæroidea by the possession of six radial spines, which are opposite in pairs in three different axes, one perpendicular to the other two. These three axes are the typical "dimensive axes," which are more or less differentiated in the Larcoidea. But in these latter the shell itself and the enclosed central capsule become affected by the unequal growth in the three axes, whilst in the former the capsule constantly, and commonly also the shell, remains spherical. Sometimes the shell assumes the form of a regular octahedron, from the six corners of which arise the six radial spines, indicating its three axes.

The most simple Cubosphærida are the Hexastylida, with one single, spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Cubosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells—two in the Hexalonchida, three in the Hexacontida, four in the Hexacromyida, five or more in the Hexacaryida. In all these four subfamilies the concentric shells are simple (not spongy), fenestrated spheres. In a sixth subfamily, in the Hexadorida, the shell is wholly or partially composed of irregular, spongy wicker-work or loose reticulations, with or without a medullary shell in the centre.

The Six Radial Spines of the Cubosphærida are normally opposite in pairs in the three dimensive axes, each of which is perpendicular to the other two. But in many species besides this normal form occur individual abnormalities, in which the six spines are not quite accurately opposed, but more or less divergent; and often also the three dimensive planes (determined each by two axes) are not quite regular, but more or less uneven. More rarely the six spines appear disposed in quite an irregular manner.

In the greater part of the Cubosphærida all six spines are quite equal, of the same size and form. But in some genera a more or less considerable differentiation takes place, so that two pairs or all three pairs of spines become different; very rarely, also both spines of one pair become unequal (probably only an individual abnormality). Those variations correspond to the differences between the crystalline systems. The common Cubosphærida, with three equal spine-pairs, correspond to the regular or cubic system, with three equal axes. The rarer forms (Hexastylarium, Hexaloncharium, Hexacontarium) exhibit two equal pairs and one different pair; they correspond to the quadratic system, with three perpendicular axes, two of which are equal, the third unequal. Still more rare are those forms (Hexastylidium, Hexalonchidium), in which all three pairs of spines are different, corresponding to the three unequal axes of the rhombic crystalline system.

Synopsis of the Genera of Cubosphærida.

I. Subfamily Hexastylida. (Shell one simple latticed sphere.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	All six radial spines simple, of equal size,			72. Hexastylus.
		Six spines of different sizes, all six simple.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Two pairs equal, one pair different,	73. Hexastylarium.
				All three pairs different,	74. Hexastylidium.
II. Subfamily Hexalonchida. (Shell composed of two concentric latticed spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	All six radial spines of equal size.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Spines simple,	75. Hexalonche.
				Spines branched,	76. Hexancistra.
		Six spines simple, in pairs of different sizes.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Two pairs equal, one pair different,	77. Hexaloncharium.
				All three pairs different,	78. Hexalonchidium.
III. Subfamily Hexacontida. (Shell composed of three spheres.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	All six radial spines of equal size.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Spines simple,	79. Hexacontium.
				Spines branched,	80. Hexadendron.
		Six spines simple, of different sizes.		Two pairs equal, one pair different,	81. Hexacontarium.
IV. Subfamily Hexacromyida. (Four concentric spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	All six radial spines of equal size.		Spines simple, no branched,	82. Hexacromyum.
V. Subfamily Hexacaryida. (Five or more spheres.)	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	All six radial spines of equal size.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Spines simple,	83. Cubosphæra.
				Spines branched,	84. Hexacaryum.
VI. Subfamily Hexadorida. (Shell a spongy sphere, with or without an enclosed central medullary shell.)	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right\}\,}$	All six radial spines of equal size, simple (not branched).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Without latticed medullary shell,	85. Cubaxonium.
				With one single medullary shell,	86. Hexadoras.
				With two medullary shells,	87. Hexadoridium.

Subfamily Hexastylida,^[76] Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.—Cubosphærida with one single spherical lattice-shell.

Genus 72. Hexastylus,^[77] Haeckel, 1881, Prodromus, p. 450.

Definition.—Cubosphærida with one simple lattice-sphere and six simple spines of equal size.

The genus Hexalonche is the most simple form of all Cubosphærida, and may be regarded as the common ancestral form of this family. It can be derived phylogenetically from Cenosphæra, by development of six radial spines on the surface of the simple spherical lattice-shell. These six simple spines are of equal size and opposite in pairs in the three dimensive axes, corresponding to the three equal axes of a cubic crystal.

Subgenus 1. Hexastylanthus, Haeckel.

Definition.—Pores regular or subregular, of nearly equal size and form; surface of the cortical shell smooth, without radial by-spines (other than the six main spines).

1. Hexastylus phænaxonius, n. sp. (Pl. 21, fig. 3).

Shell thin walled, with smooth surface. Pores subregular, hexagonal, five to six times as broad as the bars; nine to ten on the radius. Six spines triangular pyramidal, as long as the radius of the shell, as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.13, pores 0.008 to 0.01, bars 0.0015; length of the spines 0.07, basal breadth 0.008 to 0.012.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Hexastylus sapientum, n. sp.

Shell thin walled, with smooth surface. Pores regular, hexagonal, eight to ten times as broad as the bars; six to seven on the radius. Six spines bristle-shaped, longer than the diameter of the shell. (Lattice-work and spines similar to those of Heliosphæra actinota, Monogr. d. Radiol., Taf. ix. fig. 3.)

Dimensions.—Diameter of the shell 0.15, pores 0.016, bars 0.002; length of the spines 0.2, breadth 0.002.

Habitat.—North Atlantic, Station 354, surface.

3. Hexastylus thaletis, n. sp. (Pl. 21, fig. 4).

Shell thin walled, with smooth surface. Pores subregular, circular, hexagonally framed, somewhat funnel-shaped, of the same breadth as the bars; eight to nine on the radius. Six spines triangular pyramidal, with prominent edges, as long as the radius, three to four times as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.1, pores and bars 0.005; length of the spines 0.05, basal breadth 0.02.

Habitat.—Tropical Pacific, Station 225, depth 4575 fathoms.

4. Hexastylus favosus, n. sp.

Shell thick walled, with smooth surface. Pores regular, circular, hexagonally framed, deep funnel-shaped, of the same breadth as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the diameter, twice as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.12, pores and bars 0.01; length of the spines 0.12, basal breadth 0.02.

Habitat.—South Atlantic, Station 320, surface.

5. Hexastylus longissimus, n. sp.

Shell thick walled, with smooth surface. Pores regular, circular, hexagonally framed, of the same breadth as the bars; five to six on the radius. Six spines triangular prismatic, extremely elongated, ten to twenty times as long as the diameter of the shell, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.08, pores and bars 0.008; length of the spines 1.0 to 1.5, breadth 0.015.

Habitat.—Tropical Atlantic, Station 347, surface.

6. Hexastylus minimus, n. sp. (Pl. 21, fig. 5).

Shell thin walled, with smooth surface. Pores subregular, circular, twice as broad as the bars; five to six on the radius. Six spines triangular pyramidal, scarcely as long as the radius, at the base half as broad as long.

Dimensions.—Diameter of the shell 0.05, pores 0.004, bars 0.002; length of the spines 0.02, basal breadth 0.01.

Habitat.—Tropical Pacific, Station 225, depth 4575 fathoms.

7. Hexastylus biantis, n. sp.

? Haliphormis hexacantha, Ehrenberg, 1872, L. N. 24, Taf. x. fig. 6.

Shell thin walled, smooth. Pores regular, circular, four times as broad as the bars; eight to nine on the radius. Six spines conical, as long as the radius, at the base as broad as one pore.

Dimensions.—Diameter of the shell 0.12, pores 0.012, bars 0.003; length of the spines 0.06, basal breadth 0.012.

Habitat.—Indian Ocean, Madagascar, surface, Rabbe.

8. Hexastylus pittaci, n. sp.

Shell thin walled, smooth. Pores regular, circular, ten to twelve times as broad as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the radius, as broad as one pore.

Dimensions.—Diameter of the shell 0.12, pores 0.02, bars 0.002; length of the spines 0.06, basal breadth 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

9. Hexastylus maximus, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars; twelve to sixteen on the radius. Six spines six-sided pyramidal, half as long as the radius, three times as broad as one pore.

Dimensions.—Diameter of the shell 0.3, pores 0.01, bars 0.005; length of the spines 0.08, basal breadth 0.03.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

10. Hexastylus periandri, n. sp.

Shell thick walled, smooth. Pores regular, circular, double-edged, four times as broad as the bars; six to seven on the radius. Six spines conical, as long as the radius, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.2, pores 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.025.

Habitat.—Tropical Atlantic, Station 335, depth 1425 fathoms.

Subgenus 2. Hexastylettus, Haeckel.

Definition.—Pores regular or subregular, of nearly equal size and form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped radial by-spines.

11. Hexastylus solonis, n. sp. (Pl. 21, fig. 11).

Shell thick walled, covered with numerous bristle-shaped radial spines (one-third to one-half as long as the six main spines, arising from the lattice-knots). Pores regular, circular, enclosed by prominent, hexagonal frames, four to six times as broad as the bars; seven to eight on the radius. Six main spines triangular pyramidal, with spirally contorted prominent edges, as long as the radius, as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.13, pores 0.01, bars 0.002; length of the spines 0.06 to 0.8, basal breadth 0.01.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

12. Hexastylus cochleatus, n. sp. (Pl. 21, fig. 1).

Shell thick walled, covered with numerous short, conical spines (about as large as one pore). Pores regular, circular, three times as broad as the bars; eight to nine on the radius. Six main spines triangular pyramidal, with prominent, spirally-twisted edges, as long as the diameter of the shell, and twice as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.17, pores 0.015, bars 0.005; length of the spines 0.16, breadth 0.03.

Habitat.—Mediterranean, Corfu, Haeckel, surface.

13. Hexastylus setosus, Haeckel.

Acanthosphæra setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ix. fig. 11.

Shell thin walled, covered with numerous short, bristle-shaped spines (not larger than one pore). Pores regular, circular, four times as broad as the bars; thirteen to sixteen on the radius. Six main spines three-sided pyramidal, scarcely one-third as long as the radius. (In the figure of Ehrenberg, loc. cit., only four spines are in regular, crossed disposition, two others opposite in oblique direction; this is either an individual abnormality, or an error of drawing; the same species occurs with six spines exactly regularly disposed in the three dimensive axes.)

Dimensions.—Diameter of the shell 0.15; pores 0.008, bars 0.002; length of the spines 0.02 to 0.03, basal breadth 0.005.

Habitat.—Indian Ocean, Zanzibar, Pullen; Madagascar, Rabbe.

14. Hexastylus chilonis, n. sp.

Shell thin walled, covered with numerous bristle-shaped spines (as long as the radius). Pores regular, circular, twice as broad as the bars; eight to nine on the radius. Six main spines triangular pyramidal, with straight edges, as long as the diameter of the shell, as broad as two pores.

Dimensions.—Diameter of the shell 0.2, pores 0.02, bars 0.01; length of the spines 0.2, basal breadth 0.05.

Habitat.—South Atlantic, Station 325, surface.

15. Hexastylus cleobuli, n. sp.

Shell thick walled, covered with numerous short, conical spines (twice as large as one pore). Pores regular, circular, of the same breadth as the bars; twelve to thirteen on the radius. Six main spines conical, as long as the radius, three times as broad as one pore.

Dimensions.—Diameter of the shell 0.24, pores and bars 0.005; length of the spines 0.12, basal breadth 0.016.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Subgenus 3. Hexastylissus, Haeckel.

Definition.—Pores irregular, of unequal size or form; surface of the spherical shell smooth, without radial by-spines (other than the six main spines).

16. Hexastylus triaxonius, n. sp. (Pl. 21, fig. 2).

Shell thin walled, with smooth surface. Pores irregular, polygonal, three to six times as broad as the bars; four to six on the radius. Six spines triangular pyramidal, as long as the diameter of the shell, as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.05, pores 0.004 to 0.008, bars 0.0015; length of the spines 0.04, basal breadth 0.006.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

17. Hexastylus dimensivus, n. sp. (Pl. 21, fig. 6).

Shell thin walled, with smooth surface. Pores irregular, polygonal, four to eight times as broad as the bars; eleven to thirteen on the radius. Six spines hexagonal pyramidal, as long as the radius, about three times as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.13, pores 0.006 to 0.009, bars 0.0012; length of the spines 0.06, basal breadth 0.025.

Habitat.—North Pacific, Station 256, depth 2950 fathoms.

18. Hexastylus brevispinus, n. sp.

Shell thin walled, with smooth surface. Pores irregular, roundish, two to four times as broad as the bars; six to eight on the radius. Six spines triangular pyramidal, half as long as the radius, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.2, pores 0.008 to 0.016, bars 0.004; length of the spines 0.05, basal breadth 0.025.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

19. Hexastylus longispinus, n. sp.

Shell thick walled, smooth. Pores irregular, roundish, two to three times as broad as the bars; three to four on the radius. Six spines triangular prismatical, two to three times as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.08, pores 0.008 to 0.012, bars 0.004; length of the spines 0.2, breadth 0.01.

Habitat.—North Atlantic, Station 353, surface.

20. Hexastylus marginatus, n. sp. (Pl. 21, fig. 10).

Shell thick walled, rough. Pores irregular, roundish, somewhat funnel-shaped double-edged, two to three times as broad as the bars; twelve to fourteen on the radius. Six spines three-sided pyramidal, somewhat longer than the radius, three times as broad as one pore.

Dimensions.—Diameter of the shell 0.15, pores 0.007 to 0.01, bars 0.004; length of the spines 0.1, basal breadth 0.025.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

21. Hexastylus conifer, n. sp.

Shell thick walled, rough. Pores irregular, roundish, scarcely broader than the bars; fifteen to sixteen on the radius. Six spines conical, as long as the radius, five to seven times as broad as one pore.

Dimensions.—Diameter of the shell 0.18, pores and bars 0.004 to 0.006; length of the spines 0.1, basal breadth 0.03.

Habitat.—Indian Ocean, Sunda Strait, Rabbe, surface.

Subgenus 4. Hexastylurus, Haeckel.

Definition.—Pores irregular, of unequal size or form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped by-spines.

22. Hexastylus dictyotus, n. sp. (Pl. 21, figs. 8, 9).

Shell thin walled, spiny; short spines conical, smaller than the pore-breadth. Pores irregular, polygonal, five to seven times as broad as the bars; four to six on the radius. Six spines triangular pyramidal, longer than the radius, about as broad as one smaller pore.

Dimensions.—Diameter of the shell 0.09, pores 0.01 to 0.015, bars 0.002; length of the spines 0.06, basal breadth 0.01.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

23. Hexastylus hirsutus, n. sp.

Shell thin walled, densely covered with bristle-shaped, radial spines, half as long as the six main spines. Pores irregular, polygonal, three to four times as broad as the bars; eight to ten on the radius. Six spines triangular pyramidal, as long as the radius, twice as broad as one pore.

Dimensions.—Diameter of the shell 0.14, pores 0.005 to 0.008, bars 0.002; length of the spines 0.06, basal breadth 0.01.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

24. Hexastylus contortus, n. sp. (Pl. 21, fig. 12).

Shell thick walled, covered with bristle-shaped, radial spines, half as long as the radius. Pores irregular, roundish, two to three times as broad as the bars; seven to eight on the radius. Six spines triangular prismatic, in the distal half spirally twisted like a cork-screw (fig. 12); longer than the diameter of the shell, about as broad as one pore.

Dimensions.—Diameter of the shell 0.12, pores 0.006 to 0.008, bars 0.003; length of the spines 0.15, breadth 0.015.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

25. Hexastylus spiralis, n. sp. (Pl. 21, fig. 7).

Shell thick walled, covered with short conical spines. Pores irregular, roundish, two to three times as broad as the bars; five to six on the radius. Six spines triangular prismatic, with three thin, spirally contorted edges, two to three times as long as the diameter of the shell, about as broad as one large pore.

Dimensions.—Diameter of the shell 0.16, pores 0.01 to 0.02, bars 0.006; length of the spines 0.3 to 0.5, basal breadth 0.02.

Habitat.—Tropical Western Pacific, Station 225, depth 4475 fathoms.

Genus 73. Hexastylarium,^[78] n. gen.

Definition.—Cubosphærida with one simple lattice-sphere and six simple spines of different sizes; one opposite pair larger than the other two.

The genus Hexastylarium differs from its probable ancestral form, Hexastylus, by the unequal growth of the six simple spines; two opposite spines of one pair being more strongly developed than the four others, which are equal. They correspond therefore to the three axes of a quadratic crystal.

1. Hexastylarium heteraxonium, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the bars; eight to ten on the radius. Six spines three-sided pyramidal, at the base as broad as one pore. Two opposite major spines longer than the shell diameter; four others scarcely as long as the radius. (Similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but differing in the unequal length of the spines.)

Dimensions.—Diameter of the shell 0.15, pores 0.12, bars 0.004; length of the two major spines 0.2, of the four minor 0.07.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Hexastylarium quadratum, n. sp.

Shell very delicate, with smooth surface, and irregular, polygonal pores, separated by very thin bars. The form of the shell is not, as commonly, a sphere, but a geometrical square octahedron, one axis (with two opposite major spines) being nearly twice as long as the other two dimensive axes; four spines, opposite by pairs in the latter, are only half as long. The eight sides of the octahedral shell are even, equilateral-triangular. Spines angular, thin.

Dimensions.—Diameter of the shell in the major axis 0.18, in the minor 0.1; length of the major spines 0.24, minor 0.12.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

3. Hexastylarium elongatum, n. sp.

Shell thick walled, with spiny surface, and with irregular, roundish pores, two to four times as broad as the bars; eight to ten on the radius. Two opposite major spines, three to four times as long as the shell diameter, whilst the four other spines are very short, scarcely as long as the radius. All six spines at the base three-sided pyramidal, the two longer being cylindrical.

Dimensions.—Diameter of the shell 0.1; length of the major spines 0.3 to 0.4, of the minor 0.04, basal breadth 0.02.

Habitat.—North Pacific, Station 244, surface.

Genus 74. Hexastylidium,^[79] Haeckel, 1881, Prodromus, p. 450.

Definition.—Cubosphærida with one simple lattice-sphere and six simple spines in pairs different; the two opposite spines of each pair equal, the three pairs unequal.

The genus Hexastylidium differs from its probable ancestral form, Hexastylus, by the unequal growth of the six simple spines; the two spines of each pair reaching the same dimensions, whilst the three pairs are different. They correspond therefore to the three axes of a rhombic crystal.

1. Hexastylidium rhomboides, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores and very thin bars. Its form is not, as commonly, a sphere, but a rhombic octahedron. The radial proportion of the three unequal dimensive axes = 1 : 2 : 4. The radial proportion of the three pairs of spines = 1 : 3 : 8. Spines thin cylindrical, at the base angular.

Dimensions.—Diameter of the major shell axis 0.2, middle 0.1, minor 0.05; length of the major spines 0.3, middle 0.12, minor 0.04.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

2. Hexastylidium spirale, n. sp.

Shell thick walled, spherical, thorny, with irregular, roundish pores, three to five times as broad as the bars; six spines very stout, prismatic (as broad as one large pore), with three ring-like, spirally convoluted edges. Two opposite major spines of extraordinary length, ten to twelve times as long as the shell diameter, the two middle opposite spines being about as long as the latter, the two minor scarcely one-third as long. (Similar to Hexastylus spiralis, Pl. 21, fig. 7, but distinguished by the very unequal length of the spines.)

Dimensions.—Diameter of the shell 0.12; length of the major spines 1 to 1.5 mm., middle 0.15, minor 0.04.

Habitat.—Central Pacific, Station 266, surface.

Subfamily Hexalonchida,^[80] Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Cubosphærida with two concentric spherical lattice-shells.

Genus 75. Hexalonche,^[81] Haeckel, 1881, Prodromus, p. 451.

Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of equal size.

The genus Hexalonche is the most simple form, and probably the common ancestral form, of all Hexalonchida, or those Cubosphærida which possess two concentric latticed spheres, connected by six radial beams. Commonly one shell is intracapsular (medullary shell) and the other extracapsular (cortical shell); but sometimes also both shells are extracapsular, and these forms may perhaps be better separated as a peculiar genus Hexadilemma. In Hexalonche all six simple spines are of equal size, and opposite by pairs in three equal dimensive axes, corresponding to the three equal axes of a tesseral crystal. It can be derived from Hexastylus by duplication of the lattice-shell.

Subgenus 1. Hexalonchara, Haeckel.

Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface smooth, without radial by-spines (other than the six main spines).

1. Hexalonche phænaxonia, n. sp.

Cortical shell thin walled, smooth; its pores regular, hexagonal, six to eight times as broad as the bars; eight to ten to twelve on the radius. Medullary shell one-third as broad, with regular, hexagonal pores of half size. Six spines triangular pyramidal, as long as the radius of the shell, at the base as broad as one pore. (Differs from Hexastylus phænaxonius, Pl. 21, fig. 3, only in the medullary shell and the six inner radial beams, connecting it with the cortical shell.)

Dimensions.—Diameter of the outer shell 0.15, pores 0.01 to 0.015, bars 0.015 to 0.02; inner shell 0.05; length of the spines 0.08, basal breadth 0.01.

Habitat.—Central Pacific, Stations 266 to 271, depth 2425 to 2925 fathoms.

2. Hexalonche rosetta, n. sp. (Pl. 25, figs. 3, 3a, 3b).

Cortical shell thick walled, smooth, two and a half time as broad as the medullary shell. Pores of the latter (fig. 3a) regular circular; eight to ten on the half meridian, about as broad as the bars between them. Pores of the outer shell regular, hexagonal, remarkable for a very peculiar form and arrangement. In the transverse section of the shell (fig. 3b) they appear as narrow, hexagonal prismatic canals, twice as high as broad, and four to five times as broad as the thin elevated bars between them. Every seven meshes form together a larger, regular hexagon (six pores surrounding one central pore). The periphery of these larger, rosette-like hexagons projects more strongly from the surface than the walls between the smaller hexagons. On the half meridian of the shell may be counted six to seven larger and eighteen to twenty smaller hexagons. The six radial beams between the two shells are thin, three-sided prismatic, not broader than the bars of the network, the prominent prolongations of which form six very strong spines of peculiar club-like shape (fig. 3), as long as the radius of the outer shell. The three wings of the club are lower in the inner, higher in the outer half; the broadest part of the spine (at the base and in the outer third) is as broad as a hexagonal rosette (equal to three meshes of the outer shell); its outer apex is pyramidal.

Dimensions.—Diameter of the outer shell 0.13, pores 0.008 to 0.01, bars 0.02; inner shell 0.05; length of the spines 0.07, distal breadth 0.03.

Habitat.—Tropical West Pacific, Station 225, depth 4475 fathoms.

3. Hexalonche favosa, n. sp.

Cortical shell thick walled, smooth, four times as broad as the medullary shell. Pores of the former regular circular, hexagonally framed, deep funnel-shaped, of the same breadth as the bars; six to eight on the radius. Six spines triangular-pyramidal, as long as the radius, at the base twice as broad as one pore. (Differs from the similar Hexastylus favosus mainly in the possession of a medullary shell.)

Dimensions.—Diameter of the outer shell 0.16, pores and bars 0.012; inner shell 0.04; length of the spines 0.08, basal breadth 0.025.

Habitat.—Equatorial Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.

4. Hexalonche octahedra, n. sp. (Pl. 22, figs. 8, 8a).

Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between the bases of the spines), and with smooth surface, three times as broad as the spherical medullary shell. Pores of the former regular circular (three times as large as those of the latter), four times as broad as the bars; five to seven on the radius. Six spines three-sided prismatic, with thickened base and cuspidated end, somewhat longer than the radius, and once to twice as broad as one pore.

Dimensions.—Diameter of the outer shell 0.11, pores 0.01, bars 0.0025; inner shell 0.04; length of the spines 0.08, bars 0.01.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Hexalonche conicornis, n. sp. (Pl. 22, fig. 2).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores of both spheres regular circular, three to four times as broad as the bars; those of the thick walled outer shell six to seven on the radius, twice as large as those of the thin walled inner shell; six radial beams between the two spheres, very thin, cylindrical; six spines short, conical, scarcely as long as the radius of the outer shell, at the base twice as broad as one pore.

Dimensions.—Diameter of the outer shell 0.12 to 0.14, pores 0.01, bars 0.003; inner shell 0.04 to 0.05; length of the spines 0.04 to 0.06, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

6. Hexalonche curvicornis, n. sp. (Pl. 25, fig. 4).

Cortical shell thick walled, smooth, not much larger than the medullary shell (= 4 : 3). Pores of both spheres regular circular, nearly of the same size, three times as broad as the bars between them; seven to nine on the radius. Six spines three-sided prismatic, inside and outside of the exterior shell of equal thickness, twice as broad as one pore, longer than the diameter of the outer shell, and in a singular manner curved like an ox horn; the three edges of each horn somewhat spirally twisted.

Dimensions.—Diameter of the outer shell 0.16, pores 0.01, bars 0.003; inner shell 0.12; length of the spines 0.2, breadth 0.02.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

7. Hexalonche brevicornis, n. sp.

Cortical shell thin walled, smooth, three times as broad as the medullary shell. Pores of the former regular circular, double-edged, six to eight times as broad as the thin bars, five to six on the radius. Six spines triangular pyramidal, as broad as one pore and only twice as long.

Dimensions.—Diameter of the outer shell 0.14, pores 0.02, bars 0.003; inner shell 0.045; length of the spines 0.05, basal breadth 0.02.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

8. Hexalonche grandis, n. sp.

Cortical shell thick walled, smooth, four times as broad as the medullary shell. Pores of the outer shell regular circular, four times as broad as the bars; thirteen to fifteen on the radius. Six spines conical, scarcely half as long as the radius, at the base as broad as one pore.

Dimensions.—Diameter of the outer shell 0.2 to 0.32, pores 0.01 to 0.02, bars 0.003 to 0.005; inner shell 0.06 to 0.08; length of the spines 0.06, breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subgenus 2. Hexalonchetta, Haeckel.

Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface covered with numerous conical or bristle-shaped radial by-spines.

9. Hexalonche amphisiphon, n. sp. (Pl. 25, figs. 2, 2a, 2b).

Cortical shell thin walled, armed with very numerous bristle-shaped, radial by-spines, a quarter to a half as long as the six main spines. Pores regular hexagonal, twelve to fourteen on the radius, with very thin bars, prolonged on the outer as well as the inner surface into a short truncated conical tube (Pl. 25, fig. 2b). Medullary shell octahedral, with irregular polygonal meshes and very thin bars between them (fig. 2a), connected with the outer (six to eight times larger) shell by six very thin radial beams. These are prolonged outside into six strong pyramidal spines, nearly as long as the diameter of the outer shell, with sharp straight edges, at the base twice as broad as one pore.

Dimensions.—Diameter of the outer shell 0.15, pores 0.01, bars 0.001; inner shell 0.02; length of the spines 0.12, basal breadth 0.02.

Habitat.—Central Pacific, Station 271, surface.

10. Hexalonche anaximandri, n. sp. (Pl. 22, fig. 5).

Cortical shell thin walled, covered with short conical spines (smaller than the pores), three times as broad as the medullary shell. Pores of the outer shell subregular hexagonal, four times as broad as the bars; five to seven on the radius. Inner shell with regular hexagonal pores of half the size, connected with the outer by six strong, three-sided prismatic beams, which are prolonged outside into six very stout pyramidal spines, with three prominent edges, longer than the radius and twice as broad as one pore.

Dimensions.—Diameter of the outer shell 0.12, pores 0.01, bars 0.0025; inner shell 0.04; length of the spines 0.07, basal breadth 0.02.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

11. Hexalonche octocolpa, n. sp. (Pl. 22, figs. 6, 6a).

Cortical shell thin walled, nearly octahedral, with eight hemispherical or bosom-shaped vaultings, corresponding to the eight faces of a regular octahedron, the three axes of which are indicated by the six spines. Surface covered with short bristle-shaped spines. Pores regular hexagonal, ten to fifteen times as broad as the thin bars; seven to nine on the radius. Medullary shell (fig. 6a) spherical, with regular circular pores, one-third as broad as the cortical shell, and connected with it by six strong triangular radial beams, which are prolonged outside into pyramidal spines, one-third as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.2, pores 0.03, bars 0.002; inner shell 0.06; length of the spines 0.06, breadth 0.02.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

12. Hexalonche cristata, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, and covered with short conical spines arising from the nodal points of elevated crests which form regular hexagonal frames around the funnel-shaped circular pores. These are two to three times as broad as the crested bars; eight to ten on the radius. Six spines three-sided pyramidal, with strong prominent edges, about as long as the radius of the shell.

Dimensions.—Diameter of the outer shell 0.16 to 0.2, pores 0.01 to 0.015, bars 0.003 to 0.005; inner shell 0.04 to 0.05; length of the spines 0.08 to 0.12, basal breadth 0.01 to 0.03.

Habitat.—Central Pacific, Station 266 to 274, depth 2350 to 2925 fathoms.

13. Hexalonche serrata, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with spiny surface. Pores regular circular, twice as broad as the bars, five to seven on the radius, funnel-shaped, separated by hexagonal frames, the sharp crests of which are serrated; at the nodal-points longer bristle-shaped by-spines. Six main spines triangular prismatic, longer than the diameter of the shell, twice as broad as one pore.

Dimensions.—Diameter of the outer shell 0.15, pores 0.01, bars 0.005; inner shell 0.04; length of the spines 0.2, breadth 0.02.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

14. Hexalonche anaximenis, n. sp. (Pl. 25, fig. 5).

Cortical shell thin walled, twice as broad as the medullary shell, and covered with short conical by-spines. Pores regular circular, twice as broad as the bars; five to six on the radius. Circular pores of the medullary shell one-third as broad. Radial main spines conical, nearly as long as the radius of the shell.

Dimensions.—Diameter of the outer shell 0.1, pores 0.01, bars 0.005; inner shell 0.05; length of the spines 0.04, basal breadth 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

15. Hexalonche aspera, n. sp.

Cortical shell thin walled, three times as broad as the medullary shell, and covered with short conical spines. Pores regular circular, four to six times as broad as the bars; eight to ten on the radius. Radial spines conical, about as long as the diameter of the shell.

Dimensions.—Diameter of the outer shell 0.12, pores 0.08, bars 0.0015; inner shell 0.04; length of the spines 0.1, basal breadth 0.02.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

16. Hexalonche castanella, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with numerous short conical spines. Pores regular circular, twice as broad as the bars; ten to twelve on the radius. Radial spines triangular pyramidal, about as long as the radius of the shell.

Dimensions.—Diameter of the outer shell 0.22, pores 0.01, bars 0.005; inner shell 0.045; length of the spines 0.12, basal breadth 0.02.

Habitat.—North Atlantic, Station 353, depth 3125 fathoms.

Subgenus 3. Hexalonchilla, Haeckel.

Definition.—Pores of the cortical shell irregular, of unequal size or form; surface smooth, without radial by-spines (other than the six main spines).

17. Hexalonche hexacantha, Haeckel.

Haliomma hexacanthum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 35, Taf. iv. fig. 5. Haliomma hexacanthum, Haeckel, 1862, Monogr. d. Radiol., p. 430.

Cortical shell thin walled, smooth, with irregular polygonal pores (commonly hexagonal or pentagonal), two to three times as broad as the bars; eight to ten on the radius. Medullary shell one quarter as broad, connected with the former by six thin radial beams which are prolonged outside into six triangular pyramidal spines (not quadrangular, as Müller describes), longer than the radius of the shell.

Dimensions.—Diameter of the outer shell 0.2, pores 0.01 to 0.015, bars 0.005; inner shell 0.05; length of the spines 0.15, basal breadth 0.015.

Habitat.—Mediterranean (Messina, Nice, Genoa).

18. Hexalonche geometrica, n. sp.

Cortical shell thick walled, smooth, with very peculiar geometrical formation of its network, the pores of which are of very different size and form, but highly regular disposition. Each of the six triangular spines is surrounded at the base by three small roundish pores (between the three wings of its base), and further by a coronal of six very large pores, three of which are pentagonal, and the other three (alternating) heptagonal. The six basal coronals are separated by irregular smaller pores. Medullary shell thin walled, with regular hexagonal pores (three on the radius) and thin bars, connected with the outer shell by six thin triangular prismatic radial beams, which are prolonged outside into short pyramidal spines (half as long as the radius).

Dimensions.—Diameter of the outer shell 0.2, thirty-six larger pores of the coronals 0.03 to 0.04, smaller pores between them 0.01 to 0.02, bars 0.005; inner shell 0.05 (with pores of 0.008); length of the spines 0.05, basal breadth 0.03.

Habitat.—South Atlantic, off Buenos Ayres, Station 323, depth 1900 fathoms.

19. Hexalonche pythagoræa, n. sp. (Pl. 22, fig. 1).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores irregular roundish, twice to eight times as broad as the bars, of very different size; usually in the space between every three spines are three or six larger pores, separated by numerous smaller pores (often the disposition of the larger pores is much more regular than in the figured specimen). Medullary shell with regular circular pores, connected with the outer by six very thin radial beams, which are prolonged outside into six short triangular pyramidal spines about as long and broad as the half radius.

Dimensions.—Diameter of the outer shell 0.12, pores 0.008 to 0.03, bars 0.004; inner shell 0.04; length of the spines 0.04, basal breadth 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

20. Hexalonche aristarchi, n. sp. (Pl. 22, fig. 3).

Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores irregular polygonal, of very variable size and form, twice to six times as broad as the bars; six to ten on the radius. Medullary shell with regular hexagonal pores, connected with the outer by six very thin radial beams, which are prolonged outside into six triangular pyramidal spines, nearly as long as the radius.

Dimensions.—Diameter of the outer shell 0.1, pores 0.005 to 0.02, bars 0.003; inner shell 0.025; length of the spines 0.05, basal breadth 0.01.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

21. Hexalonche ekphantæa, n. sp.

Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores irregular roundish, of very variable size and form, twice to six times as broad as the bars, ten to fifteen on the radius. Six spines cylindro-conical, longer than the diameter of the shell.

Dimensions.—Diameter of the outer shell 0.2, pores 0.004 to 0.012, bars 0.002; inner shell 0.05; length of the spine 0.3, basal breadth 0.01.

Habitat.—Indian Ocean, Sunda Strait, surface, Rabbe.

Subgenus 4. Hexalonchusa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface covered with numerous conical or bristle-shaped, radial by-spines.

22. Hexalonche philosophica, n. sp. (Pl. 22, fig. 4).

Cortical shell thin walled, covered with short conical spines, three times as broad as the medullary shell. Pores irregular polygonal, or more roundish, twice to six times as broad as the bars; six to eight on the radius. Inner shell of the same structure, pores three times smaller, connected with the outer by six very thin radial beams, which are prolonged outside into six strong, triangular pyramidal spines, as long as the radius. (Similar to Hexalonche anaximandri, Pl. 22, fig. 5, but different in the irregular network and the shorter by-spines.)

Dimensions.—Diameter of the outer shell 0.11, pores 0.005 to 0.015, bars 0.0025; inner shell 0.04; length of the spines 0.06, breadth 0.02.

Habitat.—North Atlantic, Færöe Channel, John Murray; Iceland, Krabbe, surface.

23. Hexalonche seleuci, n. sp.

Cortical shell thick walled, covered with numerous short, bristle-shaped spines. Pores of very different size and form, and of a peculiar, subregular disposition, similar to those of Hexalonche geometrica (though in this case more regular). Each of the six triangular main spines (which reach nearly the length of the radius) is surrounded at the base by three small roundish pores, and these are further supplemented by a coronal of six very large polygonal pores; the six coronals are separated by irregular rows of smaller pores. Inner shell equal to one-third of the outer. Six main spines pyramidal, as long as the radius.

Dimensions.—Diameter of the outer shell 0.16, larger pores 0.03 to 0.04, smaller pores 0.01 to 0.02, bars 0.05 to 0.01; inner shell 0.05; length of the spines 0.08, basal breadth 0.03.

Habitat.—North Atlantic, Station 354, surface.

24. Hexalonche sexaculeata, Haeckel.

Haliomma sexaculeatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 87, Taf. i. fig. 8.

Cortical shell thick walled, twice as broad as the medullary shell, and covered with short conical spines. Pores irregular polygonal (mostly hexagonal), twice to three times as broad as the bars; six to eight on the radius. Six spines triangular-pyramidal (not quadrangular), somewhat longer than the radius of the shell.

Dimensions.—Diameter of the outer shell 0.11, pores 0.06 to 0.08, bars 0.03; inner shell 0.06; length of the spines 0.07, basal breadth 0.015.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Caltanisetta.

25. Hexalonche heracliti, n. sp. (Pl. 22, fig. 7).

Cortical shell thick walled, covered with bunches of small spines, each bunch at the nodule point between every three pores composed of four to eight conical spinules. Pores irregular roundish, twice to four times as broad as the bars; four to six on the radius. Inner shell equal to one-third of the outer, connected with it by six thin radial beams, which are prolonged outside into six strong triangular spines about as long as the radius.

Dimensions.—Diameter of the outer shell 0.15, pores 0.015 to 0.03, bars 0.08; inner shell 0.05; length of the spines 0.06, basal breadth 0.02.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

26. Hexalonche xenophanis, n. sp.

Cortical shell thin walled, covered with numerous short conical spines, four times as broad as the medullary shell. Pores irregular circular, twice to eight times as broad as the bars; five to seven on the radius. Six spines conical or more cylindrical, as long as the diameter of the shell or longer.

Dimensions.—Diameter of the outer shell 0.16 to 0.24, pores 0.01 to 0.04, bars 0.005; inner shell 0.04 to 0.06; length of the spines 0.2 to 0.3, breadth 0.02.

Habitat.—Central Pacific, Stations 266 to 272, surface.

27. Hexalonche setosa, n. sp.

Cortical shell thin walled, covered with numerous bristle-shaped spines, half as long as the six main spines. Pores irregular roundish, twice to five times as broad as the bars; ten to twelve on the radius. Inner shell equal to one-fifth of the outer. Six spines conical, as long as the radius.

Dimensions.—Diameter of the outer shell 0.25, pores 0.008 to 0.02, bars 0.004; inner shell 0.05; length of the spines 0.12, basal breadth 0.03.

Habitat.—South Pacific, Station 291, surface.

28. Hexalonche hystricina, n. sp. (Pl. 25, fig. 6).

Cortical shell thick walled, covered with numerous bristle-shaped spines, half as long as the six main spines. Pores irregular roundish, twice to four times as broad as the bars; five to seven on the radius. Medullary shell with very small circular pores, one-fourth of the cortical shell, connected with it by six thin prismatic radial beams, which are prolonged outside into six strong, short, three-sided pyramidal, cuspidated spines, only half as long as the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.2, pores 0.015 to 0.03, bars 0.008; inner shell 0.05; length of the spines 0.05, basal breadth 0.02.

Habitat.—Indian Ocean, Sunda Strait, surface, Rabbe.

Genus 76. Hexancistra,^[82] Haeckel, 1881, Prodromus, p. 451.

Definition.—Cubosphærida with two concentric lattice-spheres and six branched spines of equal size.

The genus Hexancistra differs from its ancestral form, Hexalonche, in the ramification of the six radial spines. These are very different in the two subgenera; in Hexancora each spine bears only three simple lateral branches, while in Hexapitys there are three rows of verticillate lateral branches on each spine.

Subgenus 1. Hexancora, Haeckel.

Definition.—Each radial spine with three simple lateral branches only (one branch from each edge of the triangular spine).

1. Hexancistra tricuspis, n. sp. (Pl. 22, fig. 9).

Cortical shell thin walled, covered with short conical by-spines, three times as broad as the medullary shell; its pores regular circular, three times as broad as the bars; ten to twelve on the radius. Pores of the medullary shell half as large, also regular circular. The two shells connected by six thin prismatic radial beams, which are prolonged outside into six very stout main spines, three-sided prismatic, as long as the shell diameter, with three thin wing-like edges. Each edge at the distal end prolonged into a strong curved lateral branch.

Dimensions.—Diameter of the outer shell 0.13, inner 0.4; cortical pores 0.01, bars 0.003; medullary pores 0.005, bars 0.003; length of the six spines 0.13, breadth 0.02.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Hexancistra ancorata, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell; its pores regular circular, twice as broad as the bars; six to eight on the radius. Six radial spines, three-sided prismatic, as long as the shell radius, with three recurved lateral branches at the distal end like the three teeth of an anchor.

Dimensions.—Diameter of the outer shell 0.1, inner 0.05; cortical pores 0.006, bars 0.003; length of the six spines 0.05, breadth 0.02.

Habitat.—South Pacific, Station 296, depth 1825 fathoms.

3. Hexancistra triserrata, n. sp. (Pl. 22, fig. 10).

Cortical shell thin walled, thorny, twice to three times as broad as the medullary shell; the two shells connected by six strong triangular beams. Inner shell spherical, with very small, regular, circular pores; ten to twelve on the half meridian. Bars as broad as the pores. Outer shell regularly octahedral, with eight triangular perfectly regular even faces, separated by eight prominent edges; the meshes circular, regular, about twelve to fourteen on the half meridian, two to three times as broad as the bars between them. Six strong radial spines, about as long as the diameter of the outer shell, three-sided prismatic, cuspidate; their three edges prominent, serrate, spirally twisted. Each spine bears about its middle three strong flattened lateral branches, nearly perpendicular to it, not serrated, and slightly curved.

Dimensions.—Diameter of the outer shell 0.13, inner 0.045; pores of the former 0.01, of the latter 0.004; length of the spine 0.12, breadth 0.014.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

4. Hexancistra quadricuspis, n. sp. (Pl. 22, fig. 11).

Cortical shell thin walled, covered with short bristle-shaped by-spines, three and a half times as broad as the medullary shell. Pores of the latter regular circular, small; pores of the former three to six times as large, very irregular, roundish, double-edged. Six radial spines, three-sided prismatic, about as long as the shell diameter, with three wing-like, slightly twisted edges, which are prolonged towards the distal end into three curved horn-shaped branches.

Dimensions.—Diameter of the outer shell 0.17, inner 0.05; cortical pores 0.01 to 0.03, bars 0.005; medullary pores 0.003, bars 0.001; length of the spines 0.15, breadth 0.013.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 2. Hexapitys, Haeckel, 1881, Prodromus, p. 451.

Definition.—Each radial spine with three rows of verticillate lateral branches (a row arising from each edge of the spine).

5. Hexancistra mirabilis, n. sp. (Pl. 23, fig. 3).

Hexapitys mirabilis, Haeckel, 1881, Prodromus, p. 451.

Cortical shell very thin walled, three times as broad as the medullary shell. Inner shell spherical, with very delicate, subregular hexagonal meshes; seven to eight on the half diameter. Outer shell octahedral, with irregular polygonal meshes of very different size; on the surface numerous thin accessory radial spines, equal in length to its radius. Six main spines, extremely long and stout, many times longer than the diameter of the outer shell, nearly as broad as the radius of the inner shell, three-sided prismatic, with sharp, prominent, spirally twisted edges; on every edge a great number of thin lateral branches, arranged perpendicularly to it, as long as the diameter of the outer shell, and pinnated by ten to twenty pairs of delicate secondary spinules, biserial and perpendicular to the primary branches. (In the figured specimen the spherical central capsule, between both shells, was well preserved; its nucleus nearly filled the medullary shell. The thick jelly-veil around it was radially striped and octahedral.)

Dimensions.—Diameter of the outer shell 0.13, of the inner 0.05; length of the spines 0.5 to 0.8 or more, breadth 0.02.

Habitat.—Central Pacific, Station 271, surface.

Genus 77. Hexaloncharium,^[83] n. gen.

Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of different sizes; one opposite pair larger than the two others.

The genus Hexaloncharium exhibits the same relation to its ancestral form, Hexalonche, that Hexastylarium bears to Hexastylus. Two opposite spines of one pair are larger than the four others, and correspond to the three axes of a quadratic crystal.

1. Hexaloncharium octahedrum, n. sp.

Cortical shell smooth, three to four times as broad as the spherical medullary shell, each having regular circular pores, twice to three times as broad as the bars. Form of the outer shell not a sphere, but a regular octahedron, with eight congruent, equilateral triangular even faces. Two opposite spines twice as long as the shell diameter, whilst the four others are scarcely equal to it. Basal breadth of all six the same (three times as large as one pore); form, three-sided prismatic, with cuspidate distal end. (Similar to Hexalonche octahedra, Pl. 22, fig. 8, but distinct in the unequal length of the spines.)

Dimensions.—Diameter of the outer shell 0.16, inner 0.045; length of the major spine 0.3, minor 0.12, basal breadth 0.03.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Hexaloncharium philosophicum, n. sp.

Cortical shell spherical, covered with short conical by-spines, twice as broad as the medullary shell; both with regular circular pores three to four times as broad as the bars. Two major spines cylindrical, with conical apex, three times as long as the four others, which are conical and about as long as the shell radius; basal breadth of all six the same (equal to one pore). Similar to Hexalonche anaximenis (Pl. 25, fig. 5), but distinct in the enormous prolongation of two opposite spines.

Dimensions.—Diameter of the outer shell 0.12, inner 0.06; length of the two major spines 0.2, of the four minor 0.06, basal breadth 0.02.

Habitat.—Central Pacific, Station 267, depth 2700 fathoms.

3. Hexaloncharium hystricinum, n. sp.

Cortical shell spherical, three times as broad as the medullary shell, and densely covered with oblique bristle-shaped by-spines. Pores irregular roundish. Two opposite major spines three-sided prismatic, longer than the shell diameter; four minor spines pyramidal, scarcely half as long as the shell radius. (Somewhat similar to Hexalonche hystricina, but distinct in the prolongation of two major spines.)

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; length of the two major spines 0.2, four minor 0.03, basal breadth 0.02.

Habitat.—South Pacific, Station 288, surface.

Genus 78. Hexalonchidium,^[84] Haeckel, 1881, Prodromus, p. 451.

Definition.—Cubosphærida with two concentric lattice-spheres and six simple spines of different sizes in pairs; the two opposite spines of each pair equal, the three pairs unequal.

The genus Hexalonchidium exhibits the same relation to Hexalonche that Hexastylidium bears to Hexastylus; the growth of the three spine-pairs is different, whilst both spines of each pair are equal; they correspond therefore to the three axes of a rhombic crystal.

1. Hexalonchidium axonometrum, n. sp.

Cortical shell thin walled, covered with short bristle-shaped by-spines, twice as broad as the medullary shell; both with regular hexagonal meshes, twice to three times as broad as the bars (inner meshes half as broad as the outer). All three spine-pairs three-sided prismatic, of very different length but of equal breadth (equal to three pores). Major spine-pair twice as long as the shell diameter; middle pair about equal to the latter, minor scarcely half as long. (Similar to Hexalonche anaximandri, Pl. 22, fig. 5, but distinct in the different length of the spines.)

Dimensions.—Diameter of the outer shell 0.12, inner 0.06; length of the major spines 0.25, middle 0.1, minor 0.04.

Habitat.—Indian Ocean, Madagascar, surface, Rabbe.

Subfamily Hexacontida,^[85] Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.—Cubosphærida with three concentric, spherical, or octahedral lattice-shells.

Genus 79. Hexacontium, Haeckel,^[86] 1881, Prodromus, p. 452.

Definition.—Shell with three concentric lattice-spheres and six simple spines of equal size.

The genus Hexacontium, the ancestral form of the Hexacontida, is probably derived from Hexalonche by duplication of the medullary shell. As in the latter, all six spines are of equal size, opposite in pairs in the three dimensive axes, and correspond therefore to the three equal axes of a tesseral crystal.

Subgenus 1. Hexacontanna, Haeckel.

Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface smooth, without radial spines or papillæ (other than the six main spines).

1. Hexacontium phænaxonium, n. sp.

Cortical shell thin walled, smooth; its pores regular hexagonal, six to nine times as broad as the bars; twelve to sixteen on the radius. Radial proportion of the three spheres = 1 : 2 : 4. Both medullary shells of the same structure as the cortical shell, only with smaller pores. The three spheres connected by six thin radial beams, which are prolonged on the outside into six strong triangular pyramidal spines, as long as the radius of the cortical shell, and, at the base, as broad as one of its pores. (Differs from Hexastylus phænaxonius and from Hexalonche phænaxonia, Pl. 21, fig. 3, in the larger size and the triple shell.)

Dimensions.—Diameter of the outer sphere 0.2, middle 0.1, inner 0.05; cortical pores 0.008, bars 0.0012; length of the spines 0.1.

Habitat.—Central Pacific, Station 270, surface.

2. Hexacontium axotrias, n. sp. (Pl. 24, fig. 3).

Cortical shell thin walled, smooth; its pores regular circular, five to six times as broad as the bars; eleven to thirteen on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Outer medullary shell with hexagonal frames around the regular circular pores (five to six on the radius). Inner medullary shell with simple small circular pores (three on the radius). The two outer shells connected by six triangular prismatic beams, which are prolonged outside to the length of the cortical radius or more.

Dimensions.—Diameter of the outer sphere 0.2, middle 0.07, inner 0.025; cortical pores 0.016, bars 0.003; length of the spines 0.1 to 0.015, basal breadth 0.02.

Habitat.—North Pacific, Station 253, surface.

3. Hexacontium hexactis, Haeckel.

Actinomma hexactis, Stöhr, 1880, Palæontogr., vol. xxvi. p. 91, Taf. ii. fig. 7.

Cortical shell thick walled, smooth, or a little rough. Pores regular circular, of the same breadth as the bars; five to seven on the radius. Radial proportion of the three spheres = 1 : 3 : 6. Both medullary shells of the same structure, but with smaller pores. Six spines triangular pyramidal, nearly as long as the diameter of the outer shell, three times as broad at the base as one pore.

Dimensions.—Diameter of the outer sphere 0.1, middle 0.05, inner 0.016; cortical pores and bars 0.008; length of the spines 0.08, basal breadth 0.025.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.

4. Hexacontium lævigatum, n. sp. (Pl. 24, fig. 6).

Cortical shell thick walled, quite smooth. Pores regular circular, with double margins, eight to ten on the radius, of the same breadth as the smooth bars. Radial proportion of the three spheres = 1 : 2 : 6. All three spheres connected by six very thin radial beams, which are prolonged outside into six short, stout, triangular, pyramidal spines, half as long as the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.13, middle 0.04, inner 0.02; cortical pores and bars 0.008; length of the spines 0.04, basal breadth 0.02.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

5. Hexacontium triplosphærium, n. sp.

Cortical shell thick walled, smooth. Pores regular circular, three times as broad as the bars; ten to twelve on the radius. Radial proportion of the three spheres = 1 : 3 : 10. Six spines conical, about as long as the radius of the cortical shell.

Dimensions.—Diameter of the outer shell 0.16, middle 0.05, inner 0.016; cortical pores 0.012, bars 0.004; length of the spines 0.07, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

6. Hexacontium octahedrum, n. sp.

Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between the spine-bases) and with smooth surface; its pores regular circular, five to seven on the radius, four times as broad as the bars. Radial proportion of the three shells = 1 : 3 : 9. Both medullary shells spherical, with very small circular pores. Six inner bars very thin; six outer spines (their prolongations) triangular pyramidal, as long as the radius of the outer shell. (Differs from Hexalonche octahedra, Pl. 22, fig. 8, almost solely in the duplication of the medullary shell.)

Dimensions.—Diameter of the outer shell 0.12, middle 0.04, inner 0.013.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Hexacontium circumtextum, n. sp. (Pl. 25, figs. 7, 7a).

Cortical shell double, enclosing a simple medullary shell. Radial proportion of the three spheres = 3 : 10 : 12. Inner cortical shell very thick walled, with regular circular, double-edged pores, four times as broad as the bars; seven to nine on the radius. From each nodal-point between every six pores arises a small, bristle-shaped, radial spine, as long as the diameter of one pore. The distal ends of all these spines are connected by very delicate tangential threads, and consequently form by their attachment an outer cortical shell, with regular hexagonal meshes and smooth surface. Six main spines short, three-sided prismatic, scarcely as long as half the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.12, middle 0.1, inner 0.03; pores of the middle shell 0.004, bars 0.001; length of the spines 0.025, basal breadth 0.01.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 2. Hexacontella, Haeckel.

Definition.—Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface covered with numerous conical or bristle-shaped, radial spines (other than the six main spines).

8. Hexacontium hexagonale, n. sp.

Cortical shell thin walled, bristly, with very delicate network; its pores regular hexagonal, twelve to sixteen on the radius, ten to twelve times as broad as the thin thread-like bars. At each nodal-point of the network (between every three meshes) arises a bristle-shaped, radial spine, as long as the diameter of one mesh. Six main spines hexagonal, as long as the radius of the outer shell, as broad at its base as one mesh. Radial proportion of the three spheres = 1 : 2 : 4. Pores of both medullary shells also regular hexagonal, but much smaller, in the middle shell eleven to twelve, in the inner, six to seven on the half meridian.

Dimensions.—Diameter of the outer shell 0.12, of the middle 0.06, of the inner 0.03; meshes of the outer shell 0.008; length of the six spines 0.05, basal thickness 0.008.

Habitat.—Indian Ocean, Ceylon, surface, Haeckel.

9. Hexacontium favosum, n. sp. (Pl. 24, figs. 2, 2a).

Cortical shell very thick walled, spiny, with regular, honeycomb-like network; its meshes funnel-shaped, with circular inner, hexagonal outer aperture, twice as broad as the bars; five to seven on the radius. Between every three meshes (at each corner of the hexagon) arises a short radial thorn, not so long as the thickness of the shell-wall. Six radial spines very short and stout, three-sided pyramidal, scarcely half so long as the radius of the outer shell. Radial proportion of the three spheres = 1 : 2 : 5. Pores of both medullary shells regular, circular, about as broad as the bars, six to eight on the half meridian.

Dimensions.—Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.05, of the inner 0.02; meshes of the outer shell 0.008; length of the six spines 0.2 to 0.3, basal breadth 0.015.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

10. Hexacontium sceptrum, n. sp. (Pl. 24, figs. 1, 1a).

Cortical shell thick walled, spiny, with regular, honeycomb-like network; its meshes funnel-shaped, with circular inner, hexagonal outer aperture, three to four times as broad as the bars; five to six on the radius. Between every three meshes arises a short radial thorn, as long as the thickness of the shell-wall. Six radial spines sceptre-shaped, six-sided, somewhat constricted towards their middle part, strong, as long as the radius of the outer shell, as broad as one of its meshes. Radial proportion of the three spheres = 1 : 2 : 6. Pores of the two inner shells regular hexagonal, with thin bars, six to eight on the half meridian (fig. 1a).

Dimensions.—Diameter of the outer shell 0.13, of the middle 0.04, of the inner 0.02; pores of the outer shell 0.01, of the middle 0.008, of the inner 0.004; length of the six spines 0.06, basal breadth 0.015.

Habitat.—Equatorial Atlantic, Station 347, surface.

11. Hexacontium prionacanthum, n. sp. (Pl. 24, figs. 7, 7a).

Cortical shell thick walled, thorny; its pores regular circular, with elevated hexagonal frames six to nine on the radius, twice as broad as the crest-shaped bars. At each nodal-point of the hexagon arises one short conical papilla or thorn. Radial proportion of the three spheres = 1 : 3 : 10. Pores of both medullary shells much smaller, regular circular. Six main spines three-sided prismatic, longer than the radius of the outer shell, as broad as one of its meshes; their three edges serrated, with ten to twelve teeth.

Dimensions.—Diameter of the outer shell 0.15, middle 0.045, inner 0.015; cortical pores 0.01, bars 0.005; length of the spines 0.1, breadth 0.012.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

12. Hexacontium clavigerum, n. sp. (Pl. 23, fig. 5).

Cortical shell very thick walled, thorny; its pores regular circular, hexagonally framed, three times as broad as the bars, nine to twelve on the radius; between them short conical papillæ or thorns arising at the nodal-points. Radial proportion of the three spheres = 1 : 2 : 5. Outer medullary shell with regular circular, much smaller pores; connected with the cortical shell by numerous (twenty to thirty) thin radial beams. Six main spines very stout, club-shaped, scarcely as long as the radius of the outer shell, three times as broad as one of its pores, three-sided, with three to four teeth on each edge.

Dimensions.—Diameter of the outer shell 0.2, of the middle 0.08, of the inner 0.04; cortical pores 0.012, bars 0.004; length of the six spines 0.08, breadth 0.03.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

13. Hexacontium floridum, n. sp. (Pl. 24, fig. 4).

Cortical shell papillose, thick walled. Pores regular, six-lobed, four times as broad as the bars, five to seven on the radius; each pore with six (sometimes also five or seven) concave indentations or lobules; between the pores at the nodal-points arise short conical papillæ or thorns. Radial proportion of the three spheres = 1 : 2 : 3. Radial main spines pommel-shaped, three-sided prismatic, longer than the radius of the outer shell, two to three times as broad as one pore.

Dimensions.—Diameter of the outer shell 0.12, middle 0.06, inner 0.03; cortical pores 0.012, bars 0.003; length of the six spines 0.08, breadth 0.03.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

14. Hexacontium hexaconicum, n. sp.

Cortical shell spiny, thick walled. Pores regular circular, of the same breadth as the bars, ten to twelve on the radius; between them long bristle-shaped by-spines, half as long as the six main spines. Radial proportion of the three spheres = 1 : 3 : 9. Six main spines conical, as long as the radius of the outer shell, four times as broad at the base as one pore.

Dimensions.—Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores and bars 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.—Antarctic Sea, Station 157, depth 1950 fathoms.

15. Hexacontium asteracanthion, Haeckel.

Haliomma asteracanthion, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 816. Actinomma asteracanthion, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiii. figs. 5, 6.

Cortical shell thin walled, spiny; its pores circular, without hexagonal frame (as a rule very regular, but in other specimens more or less irregular), often very variable in size, three to six times as broad as the bars, commonly seven to eight on the radius. Radial proportion of the three spheres = 1 : 2 : 4, or sometimes 1 : 3 : 8. Pores of the two inner shells also circular, but much smaller; those of the middle shell about half as broad, those of the inner shell one-fourth to one-sixth as broad as the pores of the outer shell. Six radial spines strong, three-sided prismatic, about as long as (or somewhat longer than) the radius of the outer shell, as broad as one of its large meshes. Accessory spines very numerous and very thin, bristle-like, usually half as long as the six main spines. (For the variability of this common species compare my Monograph, p. 442.)

Dimensions.—Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.06, of the inner 0.02 to 0.03; cortical pores 0.005 to 0.01; length of the six spines 0.06 to 0.08.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

Subgenus 3. Hexacontosa, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface smooth, without radial by-spines or papillæ (other than the six main spines).

16. Hexacontium axophænum, n. sp.

Cortical shell thin walled, smooth. Pores irregular polygonal, three to nine times as broad as the bars; seven to ten on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Both medullary shells with smaller, irregular roundish pores. Six spines three-sided pyramidal, longer than the radius of the outer shell, one to two times as broad as one larger pore.

Dimensions.—Diameter of the outer shell 0.12, middle 0.045, inner 0.015; cortical pores 0.006 to 0.018, bars 0.002; length of the spines 0.06 to 0.12, basal breadth 0.02 to 0.03.

Habitat.—Central Pacific, Stations 266 to 272, at various depths.

17. Hexacontium polygonale, n. sp.

Cortical shell thick walled, smooth. Pores irregular roundish, with polygonal frames, two to four times as broad as the bars; eight to twelve on the radius. Radial proportion of the three spheres = 1 : 3 : 10. Six spines pyramidal, nearly as long as the diameter of the outer shell, with six to nine prominent edges (along the corner number of the polygonal meshes).

Dimensions.—Diameter of the outer shell 0.2, middle 0.06, inner 0.02; cortical pores 0.008 to 0.016, bars 0.004; length of the spines 0.16 to 0.18, basal breadth 0.02.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

18. Hexacontium antarcticum, n. sp.

Cortical shell thin walled, smooth, with irregular roundish pores, eight to ten on the radius, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9. Both medullary shells with smaller roundish irregular pores. Six spines conical, pyramidal at their origin, about as long as the radius, as broad as one larger mesh.

Dimensions.—Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.12.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Hexacontura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form; surface covered with numerous conical papillæ or bristle-shaped, radial by-spines (other than the six main spines).

19. Hexacontium papillosum, n. sp. (Pl. 24, fig. 5).

Cortical shell thick walled, papillose. Pores irregular roundish, often somewhat lobed, five to six on the radius, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2.5 : 5. Both medullary shells with subregular circular pores (inner much smaller). Six radial spines short and stout, pommel or club shaped, with three prominent wings, about as long as the shell radius, and as broad as the medullary shell.

Dimensions.—Diameter of the outer shell 0.1, middle 0.05, inner 0.02, cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, bars 0.02.

Habitat.—Central Pacific, Stations 266 to 272, at various depths.

20. Hexacontium gladiatum, n. sp. (Pl. 25, fig. 8).

Cortical shell very thick walled, spiny, with irregular network; its meshes roundish, two to five times as broad as the bars, of very different size, ten to fifteen on the half meridian. Bars between them very strong, three-sided prismatic, armed with a great number of small thorns, and with large spines at the nodal-points between every three meshes. Radial proportion of the three spheres = 1 : 3 : 12. Six strong radial main spines three-sided prismatic, with three prominent, somewhat contorted wings, acute, broader than the diameter of the inner shell and as long as the diameter of the outer shell. These six main spines are situated in the same three dimensive axes as the six thin radial beams connecting the two medullary shells. But the six radial beams which connect the middle with the outer shell alternate with the former and lie in three other dimensive axes,—a very rare and remarkable disposition.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.016; cortical pores 0.01 to 0.03, bars 0.006; length of the six spines 0.2, breadth 0.02 to 0.03.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

21. Hexacontium setosum, n. sp.

Cortical shell thin walled, with numerous bristle-shaped, simple, radial by-spines of variable length. Pores irregular roundish, five to seven on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9. Main spines three-sided pyramidal, as long as the radius.

Dimensions.—Diameter of the outer shell 0.1 to 0.015, middle 0.035 to 0.05, inner 0.013 to 0.016; cortical pores 0.01 to 0.03, bars 0.003 to 0.004; length of the six spines 0.05 to 0.08, basal breadth 0.012 to 0.015.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface; also fossil in Barbados.

22. Hexacontium furcatum, n. sp.

Cortical shell thin walled, covered with numerous thin, bristle-shaped by-spines, which are forked and nearly as long as the main spines. Pores irregular roundish, eight to ten on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 2.5 : 10. Main spines triangular pyramidal, shorter then the radius.

Dimensions.—Diameter of the outer shell 0.18, middle 0.045, inner 0.018; cortical pores 0.005 to 0.015, bars 0.002; length of the six spines 0.07, basal breadth 0.015.

Habitat.—North Atlantic, Station 354, surface.

23. Hexacontium drymodes, Haeckel.

Actinomma drymodes, Haeckel, 1862, Monogr. d. Radiol., p. 442, Taf. xxiv. fig. 9.

Cortical shell thin walled, covered with numerous thin, bristle-shaped spines, which are double forked and half as long as the main spines. Pores irregular roundish, eight to ten on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Main spines three-sided prismatic, with prominent, often somewhat contorted edges, at the distal end cuspidated; longer than the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.15, middle 0.07, inner 0.035; cortical pores 0.01 to 0.03, bars 0.04; length of the six spines 0.11, basal breadth 0.03.

Habitat.—Mediterranean (Messina), surface; Canary Islands (Lanzerote); Haeckel.

24. Hexacontium periplectum, n. sp.

Cortical shell double, enclosing a simple medullary shell. Radial proportion of the three shells = 1 : 4 : 5. Inner cortical shell thick walled, with irregular roundish pores, two to eight times as broad as the bars; five to seven on the radius. Numerous radial spines, arising from it, are connected below their distal ends (at equal distances from the centre) by delicate branched threads, and so form an outer, irregular, thin, cortical shell, with spiny surface. Six main spines three-sided pyramidal, about as long as the radius.

Dimensions.—Diameter of the outer shell 0.22, middle 0.2, inner 0.045; cortical pores (of both outer shells) 0.01 to 0.03, bars 0.001 to 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.—North Pacific, Station 241, surface.

Genus 80. Hexadendron,^[87] Haeckel, 1881, Prodromus, p. 452.

Definition.—Cubosphærida with three concentric lattice-spheres and six branched spines of equal size.

The genus Hexadendron differs from Hexacontium in the ramification of the six dimensive spines, and from the similar Hexancistra in the duplication of the medullary shell. As in the latter instance, each spine can bear either three simple lateral branches or three rows of pinnate lateral branches.

1. Hexadendron quadricuspis, n. sp.

All three shells spherical, with radial proportion = 1 : 2 : 6. Pores of both medullary shells regular circular, twice as broad as the bars. Pores of the cortical shell irregular roundish, four to six times as broad as the bars; surface a little thorny. Six radial spines prismatic, with three prominent wing-like edges, which are prolonged below the distal end in three curved lateral branches. (Differs from Hexalonche quadricuspis, Pl. 22, fig. 11, mainly in the double medullary shell.)

Dimensions.—Diameter of the outer shell 0.15, middle 0.05, inner 0.025; length of the spines 0.12, breadth 0.01.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Hexadendron bipinnatum, n. sp. (Pl. 23, fig. 1).

All three shells regular octahedral, with very delicate network of irregular polygonal meshes, and very thin, thread-like bars between them; their radial proportion = 1 : 2.5 : 7.5. Surface of the cortical shell covered with numerous bristle-shaped by-spines, as long as the radius. Six main spines very large, three-sided prismatic, with three rows of pinnate, lateral branches, on the three wing-like, spirally twisted edges (similar to those of Hexancistra mirabilis, p. 189, Pl. 23, fig. 3).

Dimensions.—Diameter of the outer shell 0.12, middle 0.04, inner 0.016.

Habitat.—Central Pacific, Station 272, surface.

Genus 81. Hexacontarium,^[88] n. gen.

Definition.—Cubosphærida with three concentric lattice-spheres and six simple spines of different size; one opposite pair larger than the two others.

The genus Hexacontarium exhibits to its ancestral form Hexacontium the same relation that Hexaloncharium bears to Hexalonche; the former is developed from the latter by duplication of the medullary shell. As two opposite spines of one pair are larger than the four others, they correspond to the three axes of a quadratic crystal.

1. Hexacontarium dentatum, n. sp.

Cortical shell with regular circular, hexagonally framed pores, twice as broad as the bars, with smooth surface. Radial proportion of the three spheres = 1 : 2 : 5. Six radial spines three-sided prismatic, half as broad as the inner medullary shell, with three dentated edges. Two opposite major spines longer than the shell diameter; four other minor spines only half as long as the radius. (Similar to Hexacontium clavigerum, Pl. 23, fig. 5, but distinct by the prolongation of the spines of one axis.)

Dimensions.—Diameter of the outer shell 0.15, middle 0.06, inner 0.03; length of the major spines 0.2, minor 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Hexacontarium clavatum, n. sp.

Cortical shell covered with short conical by-spines and irregular roundish pores, three to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 8. Six radial spines three-sided prismatic, at the distal end club-shaped; two major spines three times as long as the four others, which are equal to the shell radius.

Dimensions.—Diameter of the outer shell 0.16, middle 0.06, inner 0.02.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subfamily Hexacromyida,^[89] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Cubosphærida with four concentric spherical lattice-shells.

Genus 82. Hexacromyum,^[90] Haeckel, 1881, Prodromus, p. 453.

Definition.—Cubosphærida with four concentric lattice-spheres and six simple spines of equal size.

The genus Hexacromyum possesses four concentric, spherical, or octahedral lattice-shells; two inner medullary shells within the central capsule, two outer cortical outside it. The four spheres are connected by six radial beams, which are prolonged outside into simple spines of equal size, opposite in pairs in the three dimensive axes. This genus can be derived from Hexacontium by duplication of the cortical shell.

1. Hexacromyum elegans, n. sp. (Pl. 24, fig. 9).

Shell composed of four concentric shells, with radial proportion = 1 : 2.5 : 7.5 : 10. First (innermost) shell with very small circular pores, second shell with larger circular pores. Third shell (inner cortical shell) with large, subregular, circular, hexagonally framed pores (eight to nine on the radius), twice as broad as the bars; from the elevated nodal-points of the hexagonal frames (between every three pores) arise thin bristle-shaped radial beams, which are united at the distal end by vaulted branches forming the delicate fourth shell. Surface smooth. Radial spines three-sided pyramidal, as long as the radius, as broad at the base as the innermost shell.

Dimensions.—Diameter of the four shells—(A) 0.02, (B) 0.05, (C) 0.15, (D) 0.2; length of the six radial spines 0.1, basal breadth 0.02.

Habitat.—Central Pacific, Station 271, surface.

2. Hexacromyum quadrigatum, n. sp.

Shell composed of four concentric shells, with radial proportion = 1 : 3 : 8 : 10. Structure of all four shells the same, with regular, circular pores, twice to three times as broad as the bars; size of the pores gradually increasing from the innermost to the outermost shell; surface smooth. Radial spines three-sided pyramidal, as long as the radius, half as broad at the base as the innermost shell.

Dimensions.—Diameter of the four shells—(A) 0.025, (B) 0.08, (C) 0.20, (D) 0.25; length of the spines 0.12, basal breadth 0.012.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Hexacromyum arachnoides, n. sp.

Hexacromidium arachnoides, Haeckel, 1881, Prodromus, p. 453.

Shell composed of four concentric shells, with radial proportion = 1 : 2 : 3 : 4. Innermost shell with regular, hexagonal meshes; the three other shells with irregular, polygonal meshes; bars between the large meshes in all four shells very thin, cobweb-like. Surface covered with thin bristle-shaped by-spines, as long as the radius. Six radial main spines three-sided prismatic, longer than the diameter of the whole shell.

Dimensions.—Diameter of the four shells—(A) 0.08, (B) 0.16, (C) 0.24, (D) 0.32; length of the spines 0.4, breadth 0.01.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

4. Hexacromyum octahedrum, n. sp. (Pl. 23, fig. 2).

Shell composed of four concentric shells which are not spherical (as in the three preceding species), but regular octahedral. Radial proportion = 1 : 2.5 : 6 : 9. Network in all four shells delicate, with irregular polygonal meshes and thin bars; the thickness of the bars and size of the meshes increasing from the innermost to the outermost shell. Six radial spines three-sided prismatic, increasing slowly in breadth towards the distal end, much longer than the shell diameter.

Dimensions.—Diameter of the four shells—(A) 0.02, (B) 0.05, (C) 0.12, (D) 0.18; length of the radial spines 0.2 to 0.3 and more, breadth 0.01.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Subfamily Hexacaryida,^[91] Haeckel, 1881, Prodromus, p. 454.

Definition.—Cubosphærida with five or more concentric lattice-shells.

Genus 83. Cubosphæra,^[92] n. gen.

Definition.—Cubosphærida with five to six or more concentric lattice-shells and six simple spines of equal size.

The genus Cubosphæra is developed from the preceding Hexacromyum by further addition of the concentric lattice-shells, their number amounting to five, six, or more. The innermost two of these are medullary shells, the others being cortical shells. All are connected by six radial beams, prolonged outside into six simple spines of equal size; these lie opposite in pairs in three dimensive axes, corresponding to the three axes of a cube.

1. Cubosphæra cubaxonia, n. sp. (Pl. 24, fig. 8).

Hexacromyon cubaxonium, Haeckel, 1881, Prodrom. et Atlas.

Shell composed of five concentric spheres, with the radial proportion = 1 : 3 : 8 : 10 : 13. The two medullary shells with small regular, circular pores of the same breadth as the bars. Inner cortical shell (third shell) with large regular, circular pores, four times as broad as the bars, hexagonally framed. From each hexagon-corner arises a thin bristle-shaped radial by-spine, which at a fixed distance from the centre is united with the middle cortical shell (fourth shell), which has very small circular pores. The beginning of the fifth shell (outermost) is indicated by six small reticula, produced by the six main spines at equal distances from the centre. All five shells are united by six prismatic radial beams, ending outside in pyramidal furrowed spines.

Dimensions.—Diameter of the five shells—(A) 0.2, (B) 0.15, (C) 0.12, (D) 0.045, (E) 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Cubosphæra concentrica, n. sp.

Shell composed of six concentric spheres, with the radial proportion = 1 : 2 : 6 : 7.5 : 9 : 11. The two medullary shells with regular, circular pores, twice as broad as the bars. The four cortical shells of the same structure, with irregular, roundish pores, three to four times as broad as the bars. The size of these pores and the breadth of their bars gradually increase towards the smooth surface. All six shells are connected by six thin three-sided prismatic radial beams, which are prolonged outside in six stronger spines, angular pyramidal, with smooth edges, as long as the shell radius.

Dimensions.—Diameter of the six shells—(A) 0.02 (B) 0.04, (C) 0.12, (D) 0.15, (E) 0.18, (F) 0.22.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 84. Hexacaryum,^[93] Haeckel, 1881, Prodromus, p. 454.

Definition.—Cubosphærida with five to six or more concentric lattice-shells and six branched spines of equal size.

The genus Hexacaryum is distinguished from the foregoing Cubosphæra by ramification of the six radial spines, and therefore exhibits the same relation to it that Hexancistra bears to Hexastylus, &c.

1. Hexacaryum arborescens, n. sp. (Pl. 23, figs. 4, 4a).

Shell composed of five, six, or more concentric shells, which are united by six very large radial spines. The two medullary shells spherical, inner with regular, circular, outer with irregular polygonal pores. All cortical shells (third and following) not spherical, but regular octahedral, with irregular polygonal meshes and thin bars. Radial spines prismatic, with three wing-like, spirally twisted edges, which at equal distances send out thin forked lateral branches (six on each verticil); by further ramification and communication of these branches the triangular net-plates arise, filling out the sides of the octahedral cortical shells. Diameter of all shells little different. The outer free parts of the six spines are arborescent, twice to three times as long as the enclosed inner parts, and bear six to eight verticils of free lateral branches, decreasing in size towards the distal end (similar to Arachnosphæra).

Dimensions.—Diameter of the six shells—(A) 0.015, (B) 0.04, (C) 0.1, (D) 0.16, (E) 0.22, (F) &c.; average distance of the concentric octahedra = 0.06; length of the radial spines 0.3 to 0.4 and more, breadth 0.02.

Habitat.—Central Pacific, Station 274, surface.

Subfamily Hexadorida,^[94] Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.—Cubosphærida with spongy spherical or octahedral shell (with or without enclosed concentrical lattice-shells).

Genus 85. Cubaxonium,^[95] n. gen.

Definition.—Cubosphærida with solid spongy spherical or octahedral shell, without latticed medullary shell in the centre, and with six simple radial spines of equal size.

The genus Cubosphæra may be regarded as a form of Styptosphæra, which develops six radial spines, opposite in pairs in the three dimensive axes. The solid spongy framework of the shell assumes the outer form either of a sphere, or of a regular octahedron.

1. Cubaxonium spongiosum, n. sp.

Spongy shell spherical, composed of a very dense spongy framework of nearly uniform structure; the meshes three to four times as broad as the bars; surface almost smooth. Six spines cylindrical, twice to three times as long as the diameter of the spongy sphere, about as broad as one half mesh.

Dimensions.—Diameter of the sphere 0.2, meshes 0.006 to 0.008, bars 0.002; length of the spines 0.4 to 0.5, breadth 0.004.

Habitat.—South Pacific, Station 288, surface.

2. Cubaxonium octahedrum, n. sp.

Spongy shell octahedral, composed of a loose spongy framework of nearly uniform structure; the meshes ten to twelve times as broad as the bars; surface thorny. Six spines three-sided pyramidal, longer than the diameter of the octahedron, arising from its six corners, as broad at the base as one mesh.

Dimensions.—Diameter of the shell 0.15, meshes 0.01 to 0.012, bars 0.001; length of the spines 0.2, basal breadth 0.01.

Habitat.—South Pacific, Station 300, surface.

Genus 86. Hexadoras,^[96] Haeckel, 1881, Prodromus, p. 455.

Definition.—Cubosphærida with spongy spherical shell and one simple latticed medullary shell in its centre, having six simple spines of equal size.

The genus Hexadoras exhibits the same structure of the spongy shell as Spongoplegma, but differs from it in the production of six dimensive spines. In the centre lies one simple, latticed, medullary shell, which is either spherical or octahedral. In the latter case the six spines arise from the six corners of the octahedron.

1. Hexadoras axophæna, n. sp.

Medullary shell spherical, with regular hexagonal meshes, twice as broad as the bars. Cortical shell entirely enclosing it, with loose irregular framework and thorny surface. Diameter of the outer shell three times as large as that of the inner. Six radial spines arising from the medullary shell, four to five times as long as the radius of the cortical shell, three-sided prismatic, with straight dentated edges.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; length of the spines 0.3 to 0.4.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Hexadoras lychnosphæra, n. sp.

Medullary shell spherical, with regular, circular, hexagonally framed pores, three times as broad as the bars. Cortical shell enveloping it, with loose irregular framework and spiny surface. Diameter of the outer shell eight times as large as that of the inner. Six radial spines arising from the inner shell, three-sided prismatic, with dentated, spirally contorted edges, seven times as long as the diameter of the medullary shell, with three lateral branches at the distal end (similar to Lychnosphæra, Pl. 11, fig. 1).

Dimensions.—Diameter of the outer shell 0.5, inner 0.06; total length of the spines 0.4, breadth 0.01.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

3. Hexadoras octahedrum, n. sp.

Medullary shell regular octahedral, with irregular polygonal meshes, five times as broad as the bars. Cortical shell enveloping it, with dense spongy framework, also octahedral with rough surface. Diameter of the outer shell five times as large as that of the inner. Six radial spines very long, arising from the six corners of the inner and piercing the spongy mass of the outer shell, considerably exceeding it at the free distal end, three-sided prismatic, with elegantly denticulate edges.

Dimensions.—Diameter of the outer shell 0.2, inner 0.04; total length of the spines 0.3 or more, breadth 0.02.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 87. Hexadoridium,^[97] Haeckel, 1881, Prodromus, p. 455.

Definition.—Cubosphærida with spongy spherical shell and two concentric latticed medullary shells in its centre, having six simple spines of equal size.

The genus Hexadoridium differs from Hexadoras in the duplication of the medullary shell, and exhibits therefore the same relation to it that Spongodictyon bears to Spongoplegma. In the only known species the six spines are opposite, arranged quite regularly in pairs in the three dimensive axes, and consequently represent the three axes of a regular crystal or cube.

1. Hexadoridium streptacanthum, n. sp. (Pl. 25, figs. 1, 1a).

Both medullary shells spherical, with small regular, circular pores, twice as broad as the bars; outer twice as broad as the inner. Spongy cortical shell enclosing it with dense framework, five times as broad as the outer medullary shell, regular octahedral. Six radial spines, arising from the latter, are thinned at the inner end, three to five times as long as the diameter of the cortical shell, and nearly as broad as the inner medullary shell, with three dentated and spirally contorted edges. (Very similar to the common Spongosphæra streptacantha, with irregular and variable number and dispositions of spines; possibly its ancestral form?).

Dimensions.—Diameter of the cortical shell 0.2, of the outer medullary shell 0.04, inner 0.02; length of the spines 1 mm. and more, breadth 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Family X. Astrosphærida (Pls. 11, 18-20, 26-30).

Astrosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.—Sphæroidea with numerous (eight to twelve or more, commonly between twenty and sixty) radial spines on the surface of the spherical shell; living solitary (not associated in colonies).

The family Astrosphærida, the largest and most varied of all Sphæroidea, is distinguished from the other members of this group by the possession of numerous radial spines, which are either regularly or irregularly disposed on the surface of the spherical shell. The extreme variability and richness of form in this family is mainly due to the different size, shape, and disposition of these radial spines.

The simplest Astrosphærida are the Coscinommida, with a single spherical or polyhedral lattice-shell. To this ancestral group all other subfamilies can be opposed as "Astrosphærida composita," since their skeleton is composed of two or more concentric lattice-shells: two in the Haliommida, three in the Actinommida, four in the Cromyommida, five or more in the Caryommida. In these four subfamilies the concentric shells are all simple (not spongy) fenestrated spheres or endospherical polyhedra. In the sixth subfamily, the Spongiommida, the shell is wholly or partially composed of spongy irregular wicker-work, with or without a medullary shell in the centre.

The Number of the Radial Spines in the Astrosphærida is extremely variable, and ranges from eight to forty or more; in many cases more than one hundred. Often each nodal-point of the network develops on the shell surface one spine. Still more frequently the number of the spines is less than that of the nodal-points. In all concentric Astrosphærida, having two or more concentrical shells, we can distinguish "primary spines," as outer prolongations of the inner radial beams connecting the shells, and "secondary spines," developed only on the outer surface of the shell. Naturally the former are of much greater importance than the latter. But we can also often distinguish among the latter larger "main spines" and smaller "by-spines," the latter commonly much more numerous than the former.

The Disposition of the Radial Spines, either regular or irregular, is a subject of great morphological interest, and remains to be exhausted by further observations. The following cases of regular disposition have been observed by me—(A) eight spines, opposite in pairs in four axes corresponding to the four diagonal axes of a cube; (B) nine spines, regularly disposed at equal distances (?) (not opposed in pairs); (C) ten spines, disposed at equal distances (?); (D) twelve spines, regularly disposed, corresponding to the twelve corners of the regular icosahedron; (E) fourteen spines, quite regularly disposed (six corresponding to the three axes of a regular octahedron, eight to the central points of its eight faces); (F) sixteen spines, regularly disposed (?); (G) twenty spines (very common!), either disposed in the same manner (after the law of Johannes Müller) as in the Acantharia (?), or corresponding to the twenty corners of the regular or pentagonal dodecahedron, or disposed in the same manner as in many Larcoidea (Tholonida, &c., to be described afterwards); (H) twenty-four spines, regularly disposed (?); (I) thirty-two spines, quite regularly disposed (twenty corresponding to the twenty corners of the regular dodecahedron, twelve to the central points of its twelve faces); (K) forty spines, nearly regularly (or quite symmetrically?) disposed. If the number of the spines amounts to more than forty, it is as a rule impossible to determine their regular disposition in a satisfactory manner.

Synopsis of the Genera of Astrosphærida.

I. Subfamily Coscinommida. (One single latticed shell.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Spines all simple, not branched and not tubulous.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	All spines of the same kind,	088. Acanthosphæra.
				Larger main spines and smaller by-spines,	089. Heliosphæra.
		Spines hollow conical tubes with porous walls,			090. Conosphæra.
		Between simple spines the pores prolonged in hollow tubes,			091. Coscinomma.
		Spines branched or forked.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Spines with lateral branches,	092. Cladococcus.
				Spines forked or dichotomous,	093. Elaphococcus.
II. Subfamily Haliommida. (Two concentric latticed shells.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A. Elatommida, one medullary and one cortical shell.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	All spines equal, simple,	094. Haliomma.
				All spines simple, of two different kinds,	095. Heliosoma.
				Spines branched,	096. Elatomma.
		B. Diplosphærida, both shells cortical.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	No by-spines,	097. Leptosphæra.
				Inner by-spines,	098. Diplosphæra.
				Outer by-spines,	099. Drymosphæra.
				Outer and inner by-spines,	100. Astrosphæra.
III. Subfamily Actinommida. (Three concentric latticed shells.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Radial spines not branched.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	All spines equal,	101. Actinomma.
				Larger main spines and smaller by-spines,	102. Echinomma.
		Radial spines branched or forked,			103. Pityomma.
IV. Subfamily Cromyommida. (Three concentric latticed shells.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Radial spines not branched.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	All spines equal,	104. Cromyomma.
				Larger main spines and smaller by-spines,	105. Cromyechinus.
		Radial spines branched or forked,			106. Cromyodrymus.
V. Subfamily Caryommida. (Numerous, five to ten or more, concentric latticed shells.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Two medullary shells and three or more cortical shells (lattice work ordinary),			107. Caryomma.
		No medullary shells (lattice work arachnoidal); three-sided prismatic spines, with verticils of three forked branches. (Arachnosphærida.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Triangular meshes, simple bars, without diagonal bars,	108. Arachnopila.
				Triangular meshes, simple bars; diagonal bars between the shells,	109. Arachnopegma.
				Polygonal meshes, bars branched,	110. Arachnosphæra.
VI. Subfamily Spongiommida. (Spherical shell whole or partly spongy, with or without enclosed latticed medullary shells in the centre.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	I. Tribe Spongodrymida, without latticed medullary shell.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Spongy sphere solid.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Spines simple,			111. Spongiomma.
						Spines branched,			112. Spongodrymus.
				Spongy sphere hollow.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Spines simple,			113. Spongechinus.
						Spines branched,			114. Spongothammus.
		II. Tribe Rhizoplegmida, with one single latticed medullary shell.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Medullary shell spherical.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Framework arising from the medullary shell,			115. Spongopila.
						Framework separate from the medullary shell.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	No medullary by-spines,	116. Rhizoplegma.
								Medullary by-spines,	117. Lychnosphæra.
				Medullary shell a simple cube.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Framework arising immediately from the medullary shell,			118. Centrocubus.
						Framework separate from the medullary shell,			119. Octodendron.
		III. Tribe Rhizosphærida, with two concentric latticed medullary shells.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Framework arising from the medullary shell,			120. Spongosphæra.
						Framework separate from the medullary shell,			121. Rhizosphæra.

Subfamily Coscinommida, Haeckel.

Heliosphærida, Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.—Astrosphærida with one single spherical lattice-shell.

Genus 88. Acanthosphæra,^[98] Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d.

Wiss. Berlin, p. 12.

Definition.—Astrosphærida with one simple lattice-sphere, covered with simple radial spines of the same kind.

The genus Acanthosphæra exhibits the most simple form of all Astrosphærida; a simple spherical lattice-shell, the surface of which is covered by radial spines of one and the same kind. The number of the latter is very variable, often twelve to twenty, regularly disposed; in other cases forty to sixty or more; and sometimes at each nodal-point of the network a spine is developed.

Subgenus 1. Rhaphidococcus, Haeckel, 1862, Monogr. d. Radiol., p. 365 (sensu emendato).

Definition.—Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines arising from all the nodal-points of the network.

1. Acanthosphæra tenuissima, Haeckel.

Heliosphæra tenuissima, Haeckel, 1862, Monogr. d. Radiol., p. 351, Taf. ix. fig. 2.

Shell extremely thin walled, eight to ten times as broad as one pore. Meshes or pores regular, hexagonal, with thread-like bars; five to seven on the radius. At each nodal-point (between every three meshes) arises a bristle-shaped radial spine, as long as the diameter of one pore.

Dimensions.—Diameter of the shell 0.2 to 0.25, of the meshes or pores 0.025 to 0.03, bars below 0.0001; length of the spines 0.03.

Habitat.—Mediterranean (Messina), North Atlantic (Canary Islands).

2. Acanthosphæra tenuis, n. sp.

Shell very thin walled, about twenty times as broad as one pore. Meshes subregular, hexagonal, with thread-like bars; twelve to fourteen on the radius. At each nodal-point arises a bristle-shaped radial spine, about as long as the radius.

Dimensions.—Diameter of the shell 0.3 to 0.35, pores 0.015 to 0.018, bars below 0.001; length of the spines 0.12 to 0.16.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

3. Acanthosphæra macropora, n. sp.

Shell thin walled, five to six times as broad as one mesh. Pores regular, circular, hexagonally framed, ten to twelve times as broad as the bars. Radial spines bristle-shaped, as long as the diameter of one pore, arising from all the nodal-points.

Dimensions.—Diameter of the shell 0.07 to 0.08, pores 0.012, bars 0.001; length of the spines 0.012.

Habitat.—Central Pacific, Station 271, surface.

4. Acanthosphæra micropora, n. sp.

Shell thick walled, forty to fifty times as broad as one pore. Pores regular, circular, hexagonally framed, half as broad as the bars. Radial spines bristle-shaped, as long as the radius of the shell, arising from all the nodal-points.

Dimensions.—Diameter of the shell 0.22, pores 0.003, bars 0.006; length of the spines 0.1.

Habitat.—South Pacific, Station 288, surface.

5. Acanthosphæra dentata, Haeckel.

Cladococcus dentatus, Haeckel, 1862, Monogr. d. Radiol., p. 367, Taf. xiii. fig. 10.

Shell thin walled, eight to ten times as broad as one pore. Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial spines arising from all the nodal-points of the network, three-sided prismatic, with dentated or serrated edges, longer than the shell diameter.

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.1, breadth 0.003.

Habitat.—Mediterranean (Messina), surface.

6. Acanthosphæra acufera, Haeckel.

Rhaphidococcus acufer, Haeckel, 1862, Monogr. d. Radiol., p. 366, Taf. xiv. fig. 1. Cladococcus acufer, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 800.

Shell thin walled, eight to ten times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, about as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.08.

Habitat.—Mediterranean (Messina); North Atlantic, Station 354, surface.

7. Acanthosphæra castanea, n. sp. (Pl. 26, fig. 3).

Shell thick walled, thirty times as broad as one mesh. Pores regular, circular, nearly of the same breadth as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, scarcely half as long as the radius of the shell.

Dimensions.—Diameter of the shell 0.15, pores and bars 0.005; length of the spines 0.03.

Habitat.—North Pacific, Station 244, surface.

8. Acanthosphæra flosculenta, n. sp.

Shell thick walled, thirteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars, with an elegant six-lobed frame (Pl. 28, fig. 1b). In the intervals between the six lobes of each mesh arise six conical radial spines (half as long as the radius), six around each pore. (Differs from the similar Haliomma flosculentum, Pl. 28, fig. 1, in the absence of an enclosed medullary shell and the stronger development of the spines.)

Dimensions.—Diameter of the shell 0.13, pores 0.01, bars 0.003; length of the spines 0.03.

Habitat.—Indian Ocean, Cocos Islands, surface, Rabbe.

Subgenus 2. Rhaphidocapsa, Haeckel.

Definition.—Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines scattered at some distance apart, not at all the nodal-points.

9. Acanthosphæra insignis, Haeckel.

Heliosphæra insignis, R. Hertwig, 1879, Organismus der Radiol., p. 40, Taf. v. fig. 7.

Shell thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, ten to twelve times as broad as the bars. Radial spines about one hundred and twenty, arising from certain nodal-points of the network, being as long as the diameter of the sphere, three-sided prismatic, with three thin denticulated edges.

Dimensions.—Diameter of the shell 0.2, pores 0.02, bars 0.002; length of the spines 0.18, breadth 0.003.

Habitat.—Cosmopolitan; Mediterranean (Messina), Atlantic (Stations 325, 347), Indian (Ceylon), Pacific (Stations 270 to 274), surface.

10. Acanthosphæra fortispina, n. sp.

Shell thin walled, about six times as broad as one mesh. Pores subregular, hexagonal, with thread-like bars; three to four on the radius. Radial spines about twenty, three-sided pyramidal, as long as the diameter, and one-third as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.06 to 0.09, pores 0.01 to 0.014, bars below 0.001; length of the spines 0.07 to 0.08, basal breadth 0.03 to 0.04.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

11. Acanthosphæra mucronata, n. sp. (Pl. 26, fig. 7).

Shell thick walled, fifteen times as broad as one pore. Pores regular, circular, hexagonally framed, funnel-shaped, three times as broad as the bars. Radial spines twenty to thirty, dagger-shaped or spindle-shaped, angular, twice as broad in the middle as one pore, about as long as the radius.

Dimensions.—Diameter of the shell 0.11, pores 0.0075, bars 0.0025; length of the spines 0.06, breadth 0.015.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

12. Acanthosphæra clavata, n. sp. (Pl. 26, fig. 8).

Shell thick walled, ten to twelve times as broad as one mesh. Pores subregular, circular, three times as broad as the bars. Radial spines twenty, club-shaped, angular, with prominent edges, twice as broad at the distal end as one pore, about as long as the radius.

Dimensions.—Diameter of the shell 0.11, pores 0.01, bars 0.003; length of the spines 0.06, breadth 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

13. Acanthosphæra marginata, n. sp.

Shell thick walled, twelve times as broad as one mesh. Pores regular, circular double-edged, four times as broad as the bars. Radial spines conical, fourteen in number, about as long as the radius, and as broad at the base as one mesh. Six spines correspond to the six corners of a regular octahedron, eight to the centre of the eight faces.

Dimensions.—Diameter of the shell 0.1, pores 0.008, bars 0.002; radial spines 0.06, basal breadth 0.01.

Habitat.—Central Pacific, Station 274, surface.

14. Acanthosphæra florida, n. sp.

Shell thick walled, fifteen times as broad as one mesh. Pores regular, circular, hexagonally lobed, separated by prominent funnel-shaped crests of half the breadth. Twenty conical radial spines, half as long as the radius, as broad at the base as one funnel.

Dimensions.—Diameter of the shell 0.15, pores 0.01, bars 0.005; length of the spines 0.04, basal breadth 0.02.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms.

15. Acanthosphæra enneacantha, n. sp.

Shell thin walled, fourteen times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Nine radial spines, regularly disposed, as long as the shell diameter, three-sided prismatic, with pyramidal apex, as broad as one mesh.

Dimensions.—Diameter of the shell 0.14, pores 0.01, bars 0.005; length of the spines 0.15, breadth 0.01.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

16. Acanthosphæra octahedralis, n. sp.

Shell thick walled, octahedral, fourteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Fourteen radial spines, regularly disposed, conical, as long as the radius of the shell, twice as broad at the base as one mesh. Six spines correspond to the six corners of a regular octahedron, eight to the central points of its eight faces.

Dimensions.—Diameter of the shell 0.14, pores 0.01, bars 0.003; length of the spines 0.08, basal breadth 0.02.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

17. Acanthosphæra compacta, n. sp.

Shell thick walled, about sixty times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Thirty to forty radial spines, three-sided pyramidal, scarcely half as long as the radius, five to six times as broad at the base as one pore.

Dimensions.—Diameter of the shell 0.24, pores 0.004, bars 0.002; length of the radial spines 0.05, basal breadth 0.02.

Habitat.—Fossil in Barbados.

Subgenus 3. Raphidodrymus, Haeckel.

Definition.—Pores of the spherical shell irregular, of different size or form. Radial spines arising from all the nodal-points of the network.

18. Acanthosphæra capillaris, n. sp.

Shell thin walled, with irregular polygonal meshes, twelve to twenty times as broad as the bars; eight to ten on the radius. Radial spines bristle-shaped, arising from all the nodal-points of the network, about as long as the diameter of the largest meshes.

Dimensions.—Diameter of the shell 0.15 to 0.2, pores 0.012 to 0.02, bars 0.001; length of the spines 0.02.

Habitat.—Central Pacific, Stations 260 to 274, surface.

19. Acanthosphæra arctica, n. sp.

Shell thin walled, with irregular roundish, polygonally framed meshes, three to four times as broad as the bars. Radial spines arising from all the nodal-points of the network, pyramidal at the base; in the distal half bristle-shaped, as long as the radius.

Dimensions.—Diameter of the shell 0.12, pores 0.006 to 0.008, bars 0.002; length of the spines 0.07.

Habitat.—Arctic Ocean, Greenland (in the stomach of Periphylla hyacinthina).

20. Acanthosphæra antarctica, n. sp.

Shell thick walled, with irregular, roundish pores, about as broad as the bars. Radial spines arising from all nodal-points of the network, conical at the base, half as long as the radius.

Dimensions.—Diameter of the shell 0.15, pores and bars 0.005 to 0.008; length of the spines 0.04.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Rhaphidosphæra, Haeckel, 1881, Prodromus, p. 450.

Definition.—Pores of the spherical shell irregular, of different size or form. Radial spines scattered at intervals, not at all the nodal-points.

21. Acanthosphæra echinoides, Haeckel.

Cyrtidosphæra echinoides, Haeckel, 1865, Zeitschr. f. wiss. Zool., xv. p. 367, Taf. xxvi. fig. 5.

Shell thin walled, with irregular polygonal or more roundish pores of very different size. Forty to fifty very large meshes, separated by rows of much smaller meshes. Radial spines forty to sixty, half as long as the shell radius, bristle-shaped, with conical bases.

Dimensions.—Diameter of the shell 0.13, larger pores 0.03, smaller 0.003; length of the spines 0.03.

Habitat.—Mediterranean (Nice), surface.

22. Acanthosphæra longispina, n. sp.

Shell thin walled, with irregular polygonal meshes, four to six times as broad as the bars; six to eight on the radius. Thirty to forty radial spines, three-sided prismatic, twice as broad as the bars, twice to three times as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.12 to 0.15, pores 0.012 to 0.02, bars 0.003; length of the radial spines 0.2 to 0.4, breadth 0.006.

Habitat.—North Pacific, Station 253, surface.

23. Acanthosphæra brevispina, n. sp.

Shell thick walled, with irregular polygonal meshes, twice to four times as broad as the bars; twelve to sixteen on the radius. Sixty to eighty radial spines, pyramidal, half as long as the radius of the shell, one-fourth as broad at the base.

Dimensions.—Diameter of the shell 0.2 to 0.22, pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

24. Acanthosphæra acanthica, Haeckel.

Cenosphæra acanthica, Stöhr, 1880, Palæontogr., vol. xxvi. p. 86, Taf. i. fig. 3.

Shell thick walled, with irregular, roundish pores, twice to three times as broad as the bars; seven to nine on the radius. Ten to twenty radial spines pyramidal, shorter than the radius, twice as broad at the base as one mesh.

Dimensions.—Diameter of the shell 0.12 to 0.16, pores 0.006 to 0.009, bars 0.003; length of the spines 0.04 to 0.06, basal breadth 0.01 to 0.015.

Habitat.—Fossil in Tertiary rocks of Sicily and Barbados.

25. Acanthosphæra haliphormis, Ehrenberg.

Acanthosphæra haliphormis, Ehrenberg, 1861, Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf. ii. fig. 1.

Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars; four to five on the radius. Twelve to twenty radial spines pyramidal, longer than the radius, scarcely as broad as one mesh at the base.

Dimensions.—Diameter of the shell 0.11, pores 0.01 to 0.02, bars 0.005; length of the spines 0.06 to 0.08, basal breadth 0.01.

Habitat.—Arctic Ocean, near Greenland, depth 1000 fathoms.

26. Acanthosphæra angulata, n. sp. (Pl. 26, fig. 4).

Shell thin walled; its pores irregular, roundish, with angular, double-edged margin, two to four times as broad as the bars; six to eight on the radius. Twenty to thirty radial spines pyramidal, angular, with prominent edges, shorter than the radius, as broad at the base as one small mesh.

Dimensions.—Diameter of the shell 0.2, pores 0.02 to 0.04, bars 0.01; length of the spines 0.06, basal breadth 0.02.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

27. Acanthosphæra conifera, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the radius. Twenty radial spines conical, regularly disposed, half as long as the radius, as broad at the base as one of the largest meshes.

Dimensions.—Diameter of the shell 0.2, pores 0.008 to 0.02, bars 0.004; length of the spines 0.05, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

28. Acanthosphæra maxima, n. sp.

Shell thick walled, with irregular, roundish pores, twice to eight times as broad as the bars; twelve to twenty on the radius. Radial spines very numerous (two to three hundred), short, conical, scarcely as long as the diameter of the largest meshes, and one-third as broad.

Dimensions.—Diameter of the shell 0.3 to 0.4, pores 0.008 to 0.03, bars 0.004; length of the radial spines 0.03, basal breadth 0.01.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

29. Acanthosphæra simplex, Haeckel.

Rhaphidococcus simplex, Haeckel, Monogr. d. Radiol., 1862, p. 366, figs. 5, 6.Taf. xiii. Cladococcus simplex, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 800.

Shell thick walled, with irregular, roundish pores, three to six times as broad as the bars; eight to nine on the radius. Forty to sixty radial spines, about as long as the diameter of the shell, three-sided prismatic, not straight, but more or less bent.

Dimensions.—Diameter of the shell 0.12, pores 0.005 to 0.012, bars 0.0015 to 0.02; length of the spines 0.12, breadth 0.003.

Habitat.—Mediterranean (Messina), surface, Haeckel.

30. Acanthosphæra gibbosa, n. sp.

Shell thin walled, rugged or tuberculate, covered by about twenty hill-shaped tubercles or protuberances with flat valleys between them. Network very delicate, with thread-like bars and irregular, polygonal pores; twenty to thirty on the radius. Radial spines very numerous, bristle-shaped, twice to three times as long as the diameter of the pores.

Dimensions.—Diameter of the shell 0.3, pores 0.01 to 0.02; length of the spines 0.02 to 0.05.

Habitat.—Central Pacific, Station 274, surface.

31. Acanthosphæra reticulata, n. sp. (Pl. 26, fig. 5).

Rhaphidosphæra reticulata, Haeckel, 1881, Prodromus.

Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars; six to eight on the radius. Surface of the bars covered with a peculiar delicate network of very fine crests. Twenty to forty radial spines, angular, pyramidal, scarcely one-third as long as the radius of the shell, as broad at the base as the bars.

Dimensions.—Diameter of the shell 0.22, pores 0.02 to 0.04, bars 0.01; length of the spines 0.04, basal breadth 0.01.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 89. Heliosphæra,^[99] Haeckel, 1862, Monogr. d. Radiol., p. 350 (sensu emendato).

Definition.—Astrosphærida with one simple lattice-sphere, covered with simple radial spines of two different kinds: larger main spines and smaller by-spines.

The genus Heliosphæra (in the mended definition here employed) differs from the foregoing Acanthosphæra in the possession of two different kinds of radial spines: larger main spines scattered on the surface or disposed regularly in limited numbers (twelve to twenty, sometimes forty to fifty or more), and smaller by-spines in much larger numbers, arising from all the nodal-points of the network (or sometimes also from its bars).

Subgenus 1. Heliosphærella, Haeckel.

Definition.—Pores of the shell regular or subregular, all of nearly equal size and similar form.

1. Heliosphæra hexagonaria, n. sp. (Pl. 26, fig. 2).

Shell very thin walled, about twenty times as broad as one pore. Meshes or pores subregular, hexagonal, with thread-like bars; fifteen to seventeen on the radius. Radial spines at the nodal-points of the network; about forty main spines three-sided pyramidal, half as broad at the base as one pore, and twice as long as the bristle-shaped by-spines, which are very numerous, and as long as the diameter of one pore.

Dimensions.—Diameter of the shell 0.25 to 0.3, of the meshes or pores 0.012 to 0.015, bars below 0.001; length of the main spines 0.03, basal breadth 0.007.

Habitat.—Central Pacific, Stations 272 to 274, depth 2350 to 2750 fathoms.

2. Heliosphæra actinota, Haeckel.

Heliosphæra actinota, Haeckel, 1862, Monogr. d. Radiol., p. 352, Taf. ix. fig. 3.

Shell very thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, with thread-like bars; six to eight on the radius. Radial spines at the nodal-points of the network, bristle-shaped, scarcely broader than the bars; about twenty main spines as long as the diameter of the shell, and numerous by-spines, only one-third to one-half as long as the former.

Dimensions.—Diameter of the shell 0.2 to 0.25, of the meshes 0.02 to 0.03, bars below 0.001; length of the main spines 0.2 to 0.3.

Habitat.—Mediterranean (Messina), Atlantic (Canaries, Azores), surface.

3. Heliosphæra echinoides, Haeckel.

Heliosphæra echinoides, Haeckel, 1862, Monogr. d. Radiol., p. 352, Taf. ix. fig. 4.

Shell thin walled, about six times as broad as one mesh. Pores regular, hexagonal, eight times as broad as the bars. Radial spines arising, not from the nodal-points of the network, but from the midst of the bars (very rare disposition!); twenty main spines regularly disposed, as long as the radius, four times as long as the numerous by-spines; all spines bristle-shaped, of the same breadth as the bars.

Dimensions.—Diameter of the shell 0.09, pores 0.015, bars 0.002; length of the main spines 0.04.

Habitat.—Mediterranean (Messina), surface, Haeckel.

4. Heliosphæra elegans, Haeckel.

Heliosphæra elegans, Haeckel, 1862, Monogr. d. Radiol., p. 353, Taf. ix. fig. 5.

Shell very thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, with thread-like bars, which are crossed by tangential bars, so that each side of a hexagon exhibits a regular rectangular cross (exactly the same as in Pl. 19, fig. 5). All radial spines bristle-shaped, as thin as the bars, and arising from the nodal-points; twenty main spines as long as the radius, numerous by-spines scarcely one-sixth as long.

Dimensions.—Diameter of the shell 0.26, pores 0.026, bars below 0.001; length of the main spines 0.13.

Habitat.—Mediterranean (Messina), surface, Haeckel.

5. Heliosphæra pectinata, n. sp. (Pl. 26, fig. 9).

Acanthosphæra pectinata, Haeckel, 1881, Atlas.

Shell thick walled, combed, about fourteen times as broad as one mesh. Pores subregular, circular, with elevated hexagonal frames, three times as broad as the bars. Radial spines very numerous and stout; thirty to forty main spines, three-sided pyramidal, nearly as long as the radius, as broad as one mesh; by-spines small, conical, everywhere scattered at the nodal-points of the network and on the high combs of the bars.

Dimensions.—Diameter of the shell 0.16, pores 0.012, bars 0.004; length of the main spines 0.07, basal breadth 0.016.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

6. Heliosphæra coronata, n. sp. (Pl. 26, figs. 6, 6a).

Acanthosphæra coronata, Haeckel, 1881, Atlas.

Shell thick walled, about ten times as broad as one mesh. Pores regular, circular, five times as broad as the bars; each pore surrounded by a regular coronal of six short, conical by-spines (fig. 6a); twenty to thirty main spines, also conical, half as long as the radius, as broad as one pore.

Dimensions.—Diameter of the shell 0.15, pores 0.015, bars 0.003; length of the main spines 0.04, basal breadth 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

7. Heliosphæra floribunda, n. sp.

Shell thick walled about ten times as broad as one mesh. Pores regular, six-lobed, twice as broad as the bars; each pore surrounded by six small conical by-spines (as in Pl. 28, figs. 1, 1b); twenty main spines regularly disposed cylindro-conical, as long as the diameter of the shell or longer.

Dimensions.—Diameter of the shell 0.15, pores 0.015, bars 0.008; length of the main spines 0.16, breadth 0.008.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

8. Heliosphæra cristata, n. sp.

Shell thick walled, about twelve times as broad as one mesh. Pores subregular, circular, twice as broad as the bars; each pore surrounded by an elegant coronal of ten to twenty small, conical by-spines; twenty main spines regularly disposed, conical, only one-third as long as the radius, as broad at the base as one mesh.

Dimensions.—Diameter of the shell 0.25, pores 0.02, bars 0.01; length of the main spines 0.04, basal breadth 0.02.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

9. Heliosphæra castanella, n. sp.

Shell thick walled, about twenty times as broad as one mesh. Pores regular, circular, of the same breadth as the bars. Whole surface densely covered with innumerable bristle-shaped by-spines, half as long as the radius; fifty to eighty main spines, conical, nearly as long as the diameter, twice as broad at the base as one pore. (Very similar to some species of Castanella, Pl. 113, but without the osculum characteristic of this Phæodarian; may be easily confounded with it.)

Dimensions.—Diameter of the shell 0.3, pores 0.015, bars 0.015; length of the main spines 0.25, basal breadth 0.03.

Habitat.—North Pacific (Japan), Station 234, surface.

Subgenus 2. Heliosphæromma, Haeckel.

Definition.—Pores of the shell irregular, of different size or form.

10. Heliosphæra polygonaria, n. sp.

Shell very thin walled, with thread-like bars and irregular, polygonal pores (having four to eight angles, commonly five to seven); eight to ten on the radius. Radial spines at all the nodal-points of the network, bristle-shaped; forty to sixty main spines, as long as the radius, twice as thick as the numerous by-spines, which are not larger than one mesh.

Dimensions.—Diameter of the shell 0.15 to 0.2, pores 0.012 to 0.02, bars 0.001; length of the main spines 0.08 to 0.1.

Habitat.—Central Pacific, Stations 266 to 272, surface.

11. Heliosphæra heteracantha, n. sp.

Shell thin walled, with irregular, polygonal pores, twice to four times as broad as the bars; six to eight on the radius. Twenty radial main spines, three-sided pyramidal, nearly as long as the diameter of the shell, as broad as a larger mesh; innumerable bristle-shaped by-spines variously distributed on the bars and at the nodal-points of the net; half as long as the radius.

Dimensions.—Diameter of the shell 0.12, pores 0.006 to 0.012, bars 0.003; length of the main spines 0.1, basal breadth 0.012.

Habitat.—Equatorial Atlantic, Station 347, surface.

12. Heliosphæra hyperionis, n. sp.

Shell thick walled. Pores irregular, roundish, with polygonal frames, three to six times as broad as the bars; twelve to fourteen on the radius. Thirty to forty main spines, angular, pyramidal, scarcely as long as the radius and twice as long as the numerous bristle-shaped by-spines.

Dimensions.—Diameter of the shell 0.24, pores 0.006 to 0.012, bars 0.002; length of the main spines 0.1, basal breadth 0.012.

Habitat.—North Pacific, Station 256, surface.

13. Heliosphæra elector, n. sp.

Shell thick walled, with irregular, roundish pores, twice to three times as broad as the bars; eight to ten on the radius. Twenty main spines, three-sided pyramidal, somewhat longer than the radius and four times as long as the short bristle-shaped by-spines.

Dimensions.—Diameter of the shell 0.12, pores 0.005 to 0.01, bars 0.003; length of the main spines 0.08, basal breadth 0.01.

Habitat.—South Atlantic, Station 325, surface.

14. Heliosphæra solaris, n. sp.

Shell thick walled, with irregular, roundish pores, about the same breadth as the bars; six to eight on the radius. Fifty to eighty main spines, conical, as long as the radius; by-spines very numerous, also conical, but only as large as one pore.

Dimensions.—Diameter of the shell 0.15, pores and bars 0.006 to 0.008; length of the main spines 0.08, basal breadth 0.012.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 90. Conosphæra,^[100] Haeckel, 1881, Prodromus, p. 451.

Definition.—Astrosphærida with one simple latticed sphere, covered with radial spines having the form of hollow cones with porous walls.

The genus Conosphæra differs from Acanthosphæra in the peculiar formation of the radial spines, which are not simple solid sticks, but hollow cones with porous walls, as immediate elevations of the hollow sphere.

1. Conosphæra platyconus, n. sp.

Pores of the shell regular, circular, twice as broad as the bars; ten to twelve on the radius. Conical spines about sixty, regular, broader than they are high, with six to nine pores in the wall.

Dimensions.—Diameter of the shell 0.16, pores 0.008, bars 0.004; length of the spines 0.012, basal breadth 0.024.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Conosphæra orthoconus, n. sp. (Pl. 12, fig. 2).

Pores of the shell irregular, roundish, twice to three times as broad as the bars; fourteen to sixteen on the radius. Conical spines about forty, regular, higher than they are broad, as long as the radius, with sixteen to twenty pores in the wall.

Dimensions.—Diameter of the shell 0.2, pores 0.008 to 0.012, bars 0.004; length of the spines 0.05, basal breadth 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Conosphæra plagioconus, n. sp. (Pl. 12, fig. 4).

Pores of the shell irregular, polygonal, twice to five times as broad as the bars; twenty to twenty-four on the radius. Conical spines about eighty, irregularly formed and scattered, with oblique (not radial) axes; about as high as broad, with eight to twelve pores in the wall.

Dimensions.—Diameter of the shell 0.25, pores 0.005 to 0.015, bars 0.003; length of the spines 0.02, basal breadth 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 91. Coscinomma,^[101] n. gen.

Definition.—Astrosphærida with one simple lattice-sphere, covered with simple radial spines; the pores between them prolonged into hollow, conical, or cylindrical tubuli.

The genus Coscinomma exhibits among the Astrosphærida the same peculiar formation that distinguishes Ethmosphæra and Sethosphæra among the Liosphærida; each pore of the simple shell is prolonged into a short conical or cylindrical tubulus, as a rule either on the outside or on the inside of the shell, but sometimes on both sides.

Subgenus 1. Coscinommarium, Haeckel.

Definition.—Pores prolonged into short tubes both on the inside as well as the outside of the shell.

1. Coscinomma amphisiphon, Haeckel (Pl. 26, figs. 1, 1a, 1b).

Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the inside as well as on the outside of the shell into a short truncated conical tube; fifteen to eighteen pores on the radius. In each hexagon-corner arises a bristle-shaped radial spine, half as long as the radius.

Dimensions.—Diameter of the shell 0.22, pores 0.01, bars 0.005; length of the spines 0.1.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 2. Coscinommidium, Haeckel.

Definition.—Pores prolonged into external tubes on the outside of the shell.

2. Coscinomma ectosiphon, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the outside of the shell into a short truncated conical tube; ten to twelve pores on the radius. In each hexagon-corner arises a short bristle-shaped spine, twice as long as the tube, one-third as long as the radius. (Very similar to Ethmosphæra conulosa, Pl. 12, fig. 5, but differs in the possession of radial spines.)

Dimensions.—Diameter of the shell 0.2, pores 0.012, bars 0.006; length of the spines 0.04, of the tubes 0.02.

Habitat.—North Pacific, Station 253, surface.

3. Coscinomma macrosiphon, n. sp.

Pores regular, circular, without hexagonal frames, of the same breadth as the bars, prolonged on the outside of the shell into a long cylindrical tube, half as long as the radius (eight to nine pores on the radius); between them bristle-shaped, at the base conical, radial spines of double length.

Dimensions.—Diameter of the shell 0.16, pores and bars 0.008; length of the spines 0.08, of the tubes 0.04.

Habitat.—Central Pacific, Station 274, surface.

Subgenus 3. Coscinommonium, Haeckel.

Definition.—Pores prolonged into internal tubes on the inside of the shell.

4. Coscinomma endosiphon, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars (fourteen to sixteen on the radius), prolonged on the inside of the shell into a short truncated cylindrical tube. In each hexagon-corner arises a thin, bristle-shaped, radial spine with pyramidal base, half as long as the radius, twice as long as the tube.

Dimensions.—Diameter of the shell 0.25, pores 0.012, bars 0.006; length of the spines 0.066, of the tubes 0.03.

Habitat.—South Pacific, Station 288, surface.

Genus 92. Cladococcus,^[102] J. Müller, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 485.

Definition.—Astrosphærida with one simple lattice-sphere, covered with branched radial spines (the stem of the spine never forked).

The genus Cladococcus, together with the following Elaphococcus, is distinguished from the other Coscinommida by the ramification of the radial spines covering the surface of the simple hollow lattice-sphere. In Cladococcus each spine sends out three or more lateral branches, which are either simple or again ramified; but the stem of the spine itself is not forked, as in Elaphococcus.

Subgenus 1. Cladococcalis, Haeckel.

Definition.—Branches of the spines simple, not ramified. Pores regular, all of nearly equal size and similar form.

1. Cladococcus arborescens, J. Müller.

Cladococcus arborescens, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 31, Taf. i. fig. 2.

Pores of the spherical shell regular, hexagonal, three times as broad as the bars; three to four on the radius. Ten to twenty spines, three-sided prismatic, two to three times as long as the shell diameter; towards the distal end each spine with three branches (one lateral simple straight branch on each edge of the spine).

Dimensions.—Diameter of the shell 0.1, pores 0.012, bars 0.004; length of the spines 0.2 to 0.3, breadth 0.02.

Habitat.—Mediterranean (Nice); North Atlantic, Canary Islands, surface.

2. Cladococcus spinifer, Haeckel.

Cladococcus spinifer, Haeckel, 1862, Monogr. d. Radiol., p. 368, Taf. xiii. fig. 9.

Pores regular, circular, hexagonally framed, three times as broad as the bars; five to six on the radius. Radial spines, arising from all the nodal-points of the network, three-sided, longer than the shell diameter, with six to twelve simple verticillate branches (two to four branches on each edge).

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.1, breadth 0.03.

Habitat.—Mediterranean (Messina), surface.

3. Cladococcus penicillus, n. sp.

Pores subregular, hexagonal, twice as broad as the bars; eight to ten on the radius. Sixty to eighty radial spines, three-sided prismatic, pencil-shaped, longer than the shell diameter; each at the distal end with a brush or pencil composed of nine to twenty-one short, simple, curved branches (three to seven on each edge).

Dimensions.—Diameter of the shell 0.1, pores 0.006, bars 0.003; length of the spines 0.12 to 0.16, breadth 0.006.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 2. Cladococcinus, Haeckel.

Definition.—Branches of the spines simple, not ramified. Pores irregular, of different size or form.

4. Cladococcus antarcticus, n. sp.

Pores irregular, polygonal, twice to four times as broad as the bars; five to six on the radius. Forty to fifty radial spines, angular, curved, of variable size and form, with three to nine irregular, simple, blunt curved branches.

Dimensions.—Diameter of the shell 0.14, pores 0.01 to 0.02, bars 0.05; length of the spines 0.1 to 0.18, breadth 0.007.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

5. Cladococcus japonicus, n. sp.

Pores irregular, roundish, of the same breadth as the bars; six to eight on the radius. Twenty to thirty radial spines, angular, longer than the shell diameter, with thirty to forty simple branches, decreasing in size from the middle part of the spine to the distal end (ten to thirteen branches on each edge).

Dimensions.—Diameter of the shell 0.12, pores and bars 0.007; length of the spines 0.15 to 0.2, breadth 0.004.

Habitat.—North Pacific (Japan), Station 240, surface.

6. Cladococcus quadricuspis, n. sp.

Pores irregular, roundish, twice to eight times as broad as the bars; eight to ten on the radius. About twenty radial spines, three-sided prismatic, as long as the shell diameter; in the proximal half simple, with smooth edges; in the distal half with three diverging simple branches, half the length of the spine, with dentated edges.

Dimensions.—Diameter of the shell 0.15, pores 0.004 to 0.016, bars 0.002; length of the spines 0.17, breadth 0.01.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 3. Cladococcodes, Haeckel.

Definition.—Branches of the spines again ramified. Pores regular, of nearly equal size and similar form.

7. Cladococcus scoparius, n. sp. (Pl. 27, fig. 2).

Pores regular, circular, three times as broad as the bars; five to six on the radius. Twenty radial spines, broom-shaped, three times as long as the shell diameter; in the proximal half simple, in the distal half branched, with three to nine branches, which are again ramified; spines and their branches with three smooth edges, not dentated.

Dimensions.—Diameter of the shell 0.055, pores 0.0075, bars 0.0025; length of the spines 0.15, basal thickness 0.007.

Habitat.—Central Pacific, Station 271, surface.

8. Cladococcus viminalis, Haeckel.

Cladococcus viminalis, Haeckel, 1862, Monogr. d. Radiol., p. 369, Taf. xiv. figs. 2, 3.

Pores regular, circular, hexagonally framed, four times as broad as the bars; five to six on the radius. Radial spines, arising from all the nodal-points of the network, twice as long as the shell diameter; in the basal half simple, in the distal half with three to six long, thin, curved branches, which are partly forked; three edges of the spines dentated.

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the radial spines 0.16, basal breadth 0.003.

Habitat.—Mediterranean (Messina).

9. Cladococcus bifurcus, Haeckel.

Cladococcus bifurcus, Haeckel, 1862, Monogr. d. Radiol., p. 368, Taf. xiii. figs. 7, 8.

Pores regular, circular, hexagonally framed, four times as broad as the bars; five to seven on the radius. Radial spines arising from all the nodal-points, three-sided prismatic, with dentated edges, longer than the shell diameter. On each spine six to nine branches, which are for the most part forked, the distal branches only being simple. (May be regarded as a further developmental stage of Cladococcus spinifer and Cladococcus viminalis.)

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.0025; length of the spines 0.1, basal breadth 0.003.

Habitat.—Mediterranean (Messina), Canary Islands, Azores, surface.

10. Cladococcus pinetum, n. sp. (Pl. 27, fig. 1).

Pores regular, circular, polygonally framed, about the same breadth as the bars: two to three on the radius. About twenty radial spines, very large, three to four times as long as the shell diameter, branched like a pine tree, with straight, stout, three-sided prismatic stem; three prominent edges dentated. On each edge five to seven lateral branches, the distal ends of which are simple, the proximal again ramified, with numerous ramules. The figured specimen is a young one, with branches but little developed.

Dimensions.—Diameter of the shell 0.06, pores and bars 0.008; length of the spines 0.2 to 0.25 breadth 0.01.

Habitat.—Central Pacific, Station 266 to 274, surface.

Subgenus 4. Cladococcurus, Haeckel.

Definition.—Branches of the spines again ramified. Pores irregular, of different size and form.

11. Cladococcus abietinus, n. sp. (Pl. 27, fig. 3).

Pores irregular, roundish, twice to four times as broad as the bars; six to ten on the radius. About twenty radial spines, two to three times as long as the shell diameter, branched like a pine tree, with straight, stout, three-sided pyramidal stem. From the dentated edges arise numerous verticillate branches, the proximal ends of which are thickly ramified. (Differs from the preceding and similar species mainly in the large size and irregular lattice-work of the shell.)

Dimensions.—Diameter of the shell 0.12 to 0.14, pores 0.006 to 0.012, bars 0.003; length of the spines 0.25 to 0.4, breadth 0.012.

Habitat.—North Pacific, Station 256, surface.

12. Cladococcus tricladus, n. sp.

Pores irregular, polygonal, twice to eight times as broad as the bars; eight to ten on the radius. About twenty radial spines, three-sided prismatic, twice as long as the shell diameter; in the proximal half simple, with smooth edges; in the distal half with three diverging curved branches, which bifurcate two to three times or ramify irregularly. (Closely related to the simpler Cladococcus quadricuspis.)

Dimensions.—Diameter of the shell 0.16, pores 0.04 to 0.016, bars 0.002; length of the spines 0.3, breadth 0.012.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

13. Cladococcus stalactites, n. sp. (Pl. 27, fig. 4).

Pores irregular, roundish, once to five times as broad as the bars; eight to ten on the radius. About twenty radial spines, very stout, longer than the shell diameter, with three wing-like, prominent smooth edges. At the middle, or in the distal half, each spine bears a verticil of three strong, irregularly formed ramified branches.

Dimensions.—Diameter of the shell 0.14, pores 0.003 to 0.015, bars 0.003; length of the spines 0.16 to 0.2, breadth 0.02.

Habitat.—West Tropical Pacific, Station 220, depth 1100 fathoms.

14. Cladococcus dendrites, n. sp. (Pl. 27, fig. 5).

Pores irregular, roundish, with denticulate margin, twice to four times as broad as the bars; eight to twelve on the radius. Fifty to eighty radial spines, three-sided prismatic, with elegantly denticulated edges; in the proximal two-thirds simple, in the distal third with a bunch of ten to twenty short simple spines (three to seven on each edge).

Dimensions.—Diameter of the shell 0.16 to 0.2, pores 0.006 to 0.012, bars 0.003; length of the spines 0.2 to 0.3, breadth 0.01.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Genus 93. Elaphococcus,^[103] Haeckel, 1881, Prodromus, p. 450.

Definition.—Astrosphærida with one simple lattice-sphere, covered with forked or dichotomously branched radial spines (the stem of the spine always forked).

The genus Elaphococcus differs from the preceding Cladococcus in the mode of ramification of the radial spines. These are forked; and the forked branches are either simple, again forked, or dichotomously ramified.

Subgenus 1. Elaphococcinus, Haeckel.

Definition.—Pores of the shell regular, of nearly equal size and similar form.

1. Elaphococcus furcatus, n. sp.

Pores of the spherical shell regular, hexagonal, four times as broad as the bars; four to five on the radius. Radial spines, arising from all the nodal-points of the network, cylindrical, as long as the radius, simply forked at the distal end; both branches half as long as the undivided part.

Dimensions.—Diameter of the shell 0.08, pores 0.01, bars 0.0025; length of the spines 0.04, breadth 0.004.

Habitat.—Tropical Atlantic, Station 348, surface.

2. Elaphococcus cervicornis, Haeckel.

Cladococcus cervicornis, Haeckel, 1862, Monogr. d. Radiol., p. 370, Taf. xiv. figs. 4-6.

Pores regular, hexagonal, ten to twenty times as broad as the bars; five to seven on the radius. Fifty to ninety radial spines (or more), arising not only from the nodal-points of the network but also from the bars between them. Each spine is cylindrical, longer than the shell diameter, and repeatedly forked (three to six times), having, therefore, numerous (thirty to sixty or more) curved branches. The distal ends of all branches fall in one spherical face.

Dimensions.—Diameter of the shell 0.07 to 0.09, pores 0.01 to 0.015, bars 0.001 to 0.015; length of the spines 0.1 to 0.15, breadth 0.005.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

3. Elaphococcus elaphoceras, n. sp.

Pores regular, circular, hexagonally framed, three to four times as broad as the bars; six to eight on the radius. At each nodal-point of the hexagon arises a short bristle-shaped, simple by-spine. In addition, there arise from the bars thirty to sixty large main spines, longer than the shell diameter, repeatedly forked in the same way as in the preceding species.

Dimensions.—Diameter of the shell 0.1, pores 0.008, bars 0.002; length of the spines 0.12, breadth 0.002.

Habitat.—Central Pacific, Station 272. depth 2600 fathoms.

4. Elaphococcus umbellifer, n. sp.

Pores regular, circular, three times as broad as the bars; ten to twelve on the radius. Twenty to forty straight cylindrical spines, as long as the shell diameter, having at the distal end a regular umbel composed of nine to twelve curved branches of equal length, which are again ramified and resemble the inflorescence of an umbelliferous plant, the distal ends of all ramules falling in a spherical face.

Dimensions.—Diameter of the shell 0.12, pores 0.006, bars 0.002; length of the spines 0.14, breadth 0.002.

Habitat.—South Atlantic, Station 325, surface.

Subgenus 2. Elaphococculus, Haeckel.

Definition.—Pores of the shell irregular, of different size or form.

5. Elaphococcus dichotomus, n. sp.

Pores irregular, polygonal, twice to four times as broad as the bars; six to eight on the radius. Thirty to sixty radial spines cylindrical, curved, as long as the shell diameter, simply forked at the distal end; both branches one-third as long as the undivided part.

Dimensions.—Diameter of the shell 0.15, pores 0.007 to 0.015, bars 0.004; length of the spines 0.2, breadth 0.004.

Habitat.—Arctic Ocean, Greenland, surface (Koch).

6. Elaphococcus umbellatus, n. sp.

Pores irregular, roundish, or polygonal, twice to five times as broad as the bars; six to eight on the radius. Forty to sixty radial spines cylindrical, curved, as long as the shell radius, having at the distal end an irregular umbel, composed of six to twelve short branches, which are irregularly ramified or forked. (Differs from the regular Elaphococcus umbellifer mainly in the irregularity.)

Dimensions.—Diameter of the shell 0.14, pores 0.007 to 0.015, bars 0.003; length of the spines 0.12, breadth 0.01.

Habitat.—South-east Pacific (Juan Fernandez), Station 299, surface.

7. Elaphococcus drymodes, n. sp.

Pores irregular, roundish, little broader than the bars; ten to twelve on the radius. Eighty to one hundred and twenty (or more) radial spines, cylindrical, three to four times as long as the shell diameter, irregularly forked or repeatedly dichotomous (each spine with forty to sixty forked branches); the distal ends of all branches fall in a spherical plane. (Differs from the regular Elaphococcus cervicornis mainly in the irregularity.)

Dimensions.—Diameter of the shell 0.1, pores and bars 0.003 to 0.008; length of the spines 0.3 to 0.4, breadth 0.01.

Habitat.—Arctic Ocean, Iceland (Steenstrup).

Subfamily Haliommida,^[104] Haeckel.

Diplosphærida, Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.—Astrosphærida with two concentric spherical lattice-shells, united by radial beams.

Genus 94. Haliomma,^[105] Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 128.

Definition.—Astrosphærida with one medullary (intracapsular) and one cortical (extracapsular) shell, which are connected by radial beams, piercing the central capsule. Shell surface covered with simple radial spines of the same kind.

The genus Haliomma, one of the oldest known Radiolarian genera, contained in the catalogue of its discoverer, Ehrenberg, a large number of very different Sphærellaria, belonging to at least sixteen different genera. We limit here the conception of the genus to those Haliommida which bear simple radial spines of one kind on the surface of the cortical shell (the latter being separated from the medullary shell by the central capsule).

Subgenus 1. Haliommantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; spines on the whole surface (commonly one spine at each nodal-point).

1. Haliomma hexagonium, n. sp.

Cortical shell four times as broad as the medullary shell, both having very thin thread-like bars, and regular, hexagonal pores (eighteen to twenty on the radius of the outer, five to six on the radius of the inner shell). The two shells connected by twenty thin thread-like radial beams. At each nodal-point of the outer shell arises a bristle-shaped radial spine, half as long as the radius. (Similar to Heliosoma radians, Pl. 28, fig. 3, but with all the spines equal.)

Dimensions.—Diameter of the outer shell 0.2, inner 0.05; pores of the outer 0.015, of the inner 0.01; length of the spines 0.05.

Habitat.—Equatorial Atlantic, Station 347, surface.

2. Haliomma arachnium, n. sp.

Cortical shell three times as broad as the medullary shell; pores of the former regular, hexagonal, with very thin thread-like bars (fourteen to sixteen on the radius); pores of the latter regular, circular, three times as broad as the bars (four to five on the radius). The two shells connected by about forty radial beams. At each nodal-point of the outer shell arises one bristle-shaped radial spine, twice as long as the diameter of one hexagonal mesh.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; pores of the outer 0.012, of the inner 0.006; length of the spines 0.025.

Habitat.—Central Pacific, Station 266, surface.

3. Haliomma favosum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, with regular, circular, hexagonally framed pores, twice as broad as the bars; eight to ten on the radius. Medullary shell with simple, circular pores, of the same breadth as the bars. At each nodal-point of the outer shell arises a short triangular spine three times as long as one pore.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; pores of the former 0.01, of the latter 0.005; bars 0.005; length of the spines 0.015.

Habitat.—Central Pacific, Station 271 to 274, surface.

4. Haliomma regulare, n. sp.

Cortical shell thin walled, nearly twice as broad as the medullary shell, and connected with it by forty to sixty thin radial beams. Both shells of the same perfectly regular structure, with an identical number of regular, circular pores, which are hexagonally framed, four times as broad as the bars, nine to eleven on the radius. The outer pores are twice as broad as the inner, exactly corresponding pores. Between every three pores of the outer surface (in each corner of the cortical hexagon) arises one short three-sided pyramidal spine, twice as long as the diameter of one pore.

Dimensions.—Diameter of the outer shell 0.2, of the inner 0.11; pores of the former 0.018, of the latter 0.009; length of the spines 0.04.

Habitat.—South Atlantic (Tristan da Cunha), Station 332, depth 2200 fathoms.

5. Haliomma melitomma, n. sp. (Pl. 20, fig. 4).

Melitomma formosum, Haeckel, 1879, Atlas, loc. cit.

Cortical shell thick walled, two and a half times as broad as the medullary shell, with regular pores of very elegant structure, twice as broad as the bars; eight to ten on the radius. The inner opening of each pore is simple, circular, the outer regular, six-lobed; corresponding to the six lobes are six short conical spines, which arise from the six corners of the regular hexagonal frames separating the pores. Pores of the medullary shell simple, circular, of the same breadth as the bars. The two shells connected only by six radial beams (in three dimensive axes).

Dimensions.—Diameter of the outer shell 0.17, of the inner 0.07; pores of the former 0.012, of the latter 0.004; length of the spines 0.005 to 0.01.

Habitat.—Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.

6. Haliomma lirianthus, n. sp. (Pl. 28, figs. 1, 1a, 1b).

Cortical shell thick walled, three times as broad as the medullary shell, with regular, rosette-shaped pores, twice as broad as the bars; eight to ten on the radius. The regular structure of the elegant pores is the same as in the preceding species, but without prominent crested frames (fig. 1b). Also the medullary shell (fig. 1a) is different, much thinner and smaller, with simple, circular pores, which are three times as broad as the bars. The two shells are connected by numerous (twenty?) radial beams.

Dimensions.—Diameter of the outer shell 0.15, of the inner 0.05; pores of the former 0.01, of the latter 0.005; length of the spines 0.005 to 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Haliomma castanea, Haeckel.

Haliomma castanea, Haeckel, 1862, Monogr. d. Radiol., p. 428, Taf. xxiv. fig. 4.

Cortical shell thick walled, three times as broad as the medullary shell; pores of both regular, circular, twice as broad as the bars (seven to eight on the radius of the outer, four to five on the radius of the inner shell), the two connected by six to twelve (?) strong radial beams. Radial spines bristle-shaped, with conical bases, twice as long as the diameter of the cortical pores (one spine at the nodal-point between every three pores).

Dimensions.—Diameter of the outer shell 0.1 to 0.15, inner 0.03 to 0.05; pores of the former 0.005, of the latter 0.003; length of the spines 0.005 to 0.01.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

8. Haliomma horridum, Stöhr.

Haliomma horridum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 87, Taf. i. fig. 10.

Cortical shell thick walled, two and a half times as broad as the medullary shell. Pores regular, circular, of the same breadth as the bars; eight to ten on the radius. Radial spines conical, stout, nearly half as long as the radius. (Differs from the closely allied Haliomma castanea in the smaller pores and larger spines.)

Dimensions.—Diameter of the outer shell 0.14, of the inner 0.06; pores of the former 0.004, of the latter 0.02.

Habitat.—Fossil in Tertiary rocks of Barbados and Sicily; living in the Atlantic, Station 9, depth 3150 fathoms, and Station 353, depth 2965 fathoms.

9. Haliomma datura, n. sp.

Cortical shell thin walled, only one and a half times as broad as the medullary shell, both having regular, circular pores, four to six times as broad as the bars (five to six on the radius of the outer, three to four on the radius of the inner shell), the two connected by numerous (forty to sixty?) thin, short, radial beams. Radial spines conical, twice as long as the diameter of one cortical pore, arising from all the nodal-points between them.

Dimensions.—Diameter of the outer shell 0.08 to 0.12, inner 0.06 to 0.08; pores of the former 0.015 to 0.02, of the latter 0.007 to 0.012; length of the spines 0.02.

Habitat.—Central Pacific, Stations 268 to 274, surface.

Subgenus 2. Haliommetta, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; the spines not covering the entire surface, but scattered at intervals (their number smaller than that of the nodal-points of the network).

10. Haliomma circumtextum, n. sp. (Pl. 28, figs. 7, 7a).

Cortical shell very delicate, with thin thread-like bars, and regular, hexagonal pores, little larger than the thick-walled medullary shell (= 7 : 6). Pores of the latter regular, circular, double-edged, with hexagonal frames, of the same breadth as the bars; from all the hexagon-corners arise thin bristle-shaped, radial spines, twice as long as the diameter of the pores, becoming connected at equal distances from the centre by tangential threads, regularly disposed, forming the cortical shell. Twelve strong, three-sided pyramidal, radial spines, as broad at the base as one mesh, and about half as long as the radius of the shell.

Dimensions.—Diameter of the outer shell 0.14, of the inner 0.12; pores of the former 0.012, of the latter 0.005; length of the radial spines 0.04, basal breadth 0.012.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

11. Haliomma duodecinum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell. Both shells with regular, circular pores, twice as broad as the bars; eight to ten on the radius of the outer, five to six on the radius of the inner shell. Twelve conical, regularly disposed radial spines, as long as the radius, and as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.005, of the latter 0.002; length of the spines 0.05, basal breadth 0.005.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

12. Haliomma megaporum, Ehrenberg.

Haliomma megaporum, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 313.

Cortical shell thin walled, three times as broad as the medullary shell; the pores regular, circular, three to four on the radius, eight times as broad as the bars, quite as broad as the medullary shell, the pores of which are much smaller, twice as broad as the bars. Eight radial spines regularly disposed, conical, as long as the radius. (As the diagnosis of Ehrenberg is very incomplete, and no figure is given with it, it remains doubtful whether his Mediterranean species be identical with my Atlantic variety.)

Dimensions.—Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.04, of the latter 0.008; length of the spines 0.06.

Habitat.—Mediterranean (Grecian shore); North Atlantic, Station 354, surface.

13. Haliomma oculatum, Ehrenberg.

Haliomma oculatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxviii. figs. 2, 3.

Cortical shell thick walled, four times as broad as the medullary shell; its pores regular, circular, four times as broad as the bars, six to eight on the radius. Pores of the medullary shell regular, hexagonal, with very thin bars, three to four on the radius. Nine radial spines, regularly disposed, conical, as long as the radius, as broad at the base as one cortical pore. (In the specimen figured by Ehrenberg, only two spines were preserved, seven being accidentally broken off.)

Dimensions.—Diameter of the outer shell 0.16, of the inner 0.04; pores of the former 0.01, of the latter 0.005.

Habitat.—Fossil in Barbados.

14. Haliomma enneaxiphos, n. sp.

Cortical shell thick walled, four times as broad as the dark medullary shell, with regular, circular, hexagonally framed pores, twice as broad as the bars; eight to ten on the radius. Nine radial spines regularly disposed, three sided pyramidal, as long as the radius, as broad at the base as one mesh.

Dimensions.—Diameter of the outer shell 0.11, of the inner 0.03; cortical pores 0.008, bars 0.004; length of the radial spines 0.05, basal breadth 0.012.

Habitat.—Central Pacific, Station 272, surface.

15. Haliomma tenuispinum, J. Müller.

Haliomma tenuispinum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf. iv. fig. 9. Haliomma tenuispinum, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Cortical shell thin walled, three times as broad as the medullary shell. Both shells with very fine, thread-like bars, and regular, hexagonal pores; five to seven on the radius. Twenty radial spines, very thin, bristle-shaped, as long as the radius.

Dimensions.—Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.016, of the latter 0.006.

Habitat.—Mediterranean (Nice); North Atlantic, Station 353, surface.

16. Haliomma longispinum, J. Müller.

Haliomma longispinum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf iv. fig. 8. Haliomma longispinum, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Cortical shell thick walled, three times as broad as the dark medullary shell. Pores regular, circular, hexagonally framed, twice as broad as the bars; four to six on the radius. Twenty radial spines, very long, regularly disposed, four to five times as long as the diameter of the shell, three-sided prismatic, with elegantly dentated edges, as broad as one cortical mesh.

Dimensions.—Diameter of the outer shell 0.08, of the inner 0.03; pores of the former 0.01, bars 0.005; length of the spines 0.3 to 0.4.

Habitat.—Mediterranean (Nice); Central Pacific, Station 272, surface.

17. Haliomma capense, n. sp.

Cortical shell thick walled, twice as broad as the medullary shell, both with regular, circular pores, twice as broad as the bars; eight to ten on the radius of the outer, four to six on the radius of the inner shell. Forty to sixty radial spines, conical, as long as the radius, as broad as one cortical pore.

Dimensions.—Diameter of the outer shell 0.11, of the inner 0.05; pores of the former 0.01, bars 0.005; length of the spines 0.006, basal breadth 0.012.

Habitat.—Cape of Good Hope, Station 142, surface.

18. Haliomma denticulatum, n. sp.

Cortical shell thick walled, three times as broad as the dark medullary shell, with regular, circular, double-edged pores, of the same breadth as the bars; eight to ten on the radius. Thirty to fifty radial spines, three-sided pyramidal, half as long as the radius, with three denticulated edges. (Very similar to Actinomma denticulatum, Pl. 29, fig. 3, but with simple medullary shell.)

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; pores and bars of the former 0.008; length of the spines 0.04, basal breadth 0.01.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

19. Haliomma grande, n. sp.

Cortical shell thick walled, five times as broad as the dark medullary shell, with small, regular, circular pores, half as broad as the bars; twenty to twenty-four on the radius. One hundred to one hundred and twenty conical radial spines, five times as long as broad, only half as long as the radius.

Dimensions.—Diameter of the outer shell 0.4, inner 0.08; pores of the outer 0.006, bars 0.012; length of the spines 0.1, basal breadth 0.02.

Habitat.—Equatorial Atlantic, Station 348, depth 2450 fathoms.

Subgenus 3. Haliommilla, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size and form; spines covering the entire surface (commonly one spine at each nodal-point).

20. Haliomma capillaceum, Haeckel.

Haliomma capillaceum, Haeckel, 1862, Monogr. d. Radiol., p. 426, Taf. xxiii. fig. 2.

Cortical shell very thin walled, seven to eight times as broad as the medullary shell, both with irregular, polygonal pores, and very thin thread-like bars; outer pores twice to three times as broad as the inner. Radial spines very numerous, straight, bristle-shaped, about as long as the diameter of the medullary shell.

Dimensions.—Diameter of the outer shell 0.2, inner 0.025 to 0.03; outer pores 0.02 to 0.04, inner 0.008 to 0.016, bars 0.001; length of the spines 0.02 to 0.03.

Habitat.—Mediterranean (Messina), Atlantic (Canary Islands), surface.

21. Haliomma erinaceum, Haeckel.

Haliomma erinaceum, Haeckel, 1862, Monogr. d. Radiol., p. 427, Taf. xxiii. figs. 3, 4.

Cortical shell thin walled, seven to eight times as broad as the medullary shell, both with irregular, polygonal pores, two to ten times as broad as the bars, outer pores much larger than the inner. Radial spines very numerous, bristle-shaped, as long as the diameter of the medullary shell, the majority or all being either curved or obliquely depressed, the greater part neither straight nor radial.

Dimensions.—Diameter of the outer shell 0.2, inner 0.025 to 0.03; outer pores 0.005 to 0.03, inner 0.008 to 0.016, bars 0.002 to 0.004; length of the spines 0.03.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

22. Haliomma tenellum, Haeckel.

Haliomma tenellum, Haeckel, 1862, Monogr. d. Radiol., p. 428. Haliomma spinuloso affine, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 40, Taf. iv. fig. 7.

Cortical shell thin walled, three times as broad as the medullary shell, with irregular, roundish pores, and very thin bars. Pores of the inner shell regular, circular. Radial spines very numerous, bristle-shaped, straight, as long as the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; outer pores 0.008 to 0.016, inner 0.005; length of the spines 0.07.

Habitat.—Mediterranean (Nice); Atlantic, Stations 349 to 354, surface.

23. Haliomma spinulosum, J. Müller.

Haliomma spinulosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf. iv. fig. 6.

Cortical shell thin walled, twice as broad as the medullary shell, with irregular, polygonal pores, and very thin bars. Pores of the inner shell subregular, hexagonal, ten to twelve times as broad as the bars. Radial spines very numerous, bristle-shaped, one-sixth to one-fourth as long as the radius of the outer shell.

Dimensions.—Diameter of the outer shell 0.16, inner 0.08; outer pores 0.01 to 0.03, inner 0.02; length of the spines 0.02 to 0.03.

Habitat.—Mediterranean (Nice); Central Pacific, Station 266, surface.

24. Haliomma rhodococcus, n. sp. (Pl. 19, fig. 6).

Sethosphæra rhodococcus, Haeckel, 1879, Atlas, pl. xix. fig. 6.

Cortical shell very thin walled, little larger than the thick walled medullary shell (= 10 : 9). Pores of the outer shell very irregular, roundish, twice to six times as broad as the bars, about twenty on the radius. Pores of the inner shell twice as broad as the bars, six to eight on the radius, very regular, circular on the inner, six-lobed on the outer opening, separated by prominent hexagonal crests; in the hexagon-corners arise short conical radial spines, which at equal distances from the centre are united by the outer shell, but are prominent over its surface. (A very peculiar form; the two shells may better be regarded as inner and outer cortical shell.)

Dimensions.—Diameter of the outer shell 0.2, inner 0.18; outer pores 0.04 to 0.012, inner 0.01; length of the spines 0.01.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; also fossil in Barbados.

25. Haliomma boreale, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with irregular, roundish pores, twice to four times as broad as the bars; eight to ten on the radius. Pores of the inner shell regular, circular, twice as broad as the bars, four to six on the radius. Radial spines very numerous, conical, nearly as long as the diameter of the shell.

Dimensions.—Diameter of the outer shell 0.24, inner 0.06; outer pores 0.008 to 0.02, bars 0.005, inner pores 0.006, bars 0.003; length of the spines 0.2.

Habitat.—Arctic Ocean, Greenland ("Alert" Expedition).

Subgenus 4. Haliommura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size and form; spines not covering the entire surface, but scattered at intervals (their number smaller than that of the nodal-points in the network).

26. Haliomma macrodoras, n. sp. (Pl. 28, figs. 6, 6a).

Cortical shell thin walled, twice as broad as the medullary shell, with irregular, polygonal meshes, three to six times as broad as the bars. Inner shell with regular, hexagonal meshes, ten times as broad as the bars. Twenty radial spines, very long, stout, three-sided prismatic, two to four times as long as the diameter of the shell, as broad as one medullary mesh, with three wing-like, denticulated edges. At the base of each spine three supporting curved beams.

Dimensions.—Diameter of the outer shell 0.14 to 0.16, of the inner 0.07 to 0.08; outer pores 0.01 to 0.02, bars 0.003; inner pores 0.01, bars 0.001; length of the spines 0.3 to 0.6, breadth 0.01.

Habitat.—Central Pacific, Station 271, surface.

27. Haliomma antarcticum, n. sp.

Cortical shell very thin walled, three times as broad as the medullary shell, with irregular, polygonal pores, and very thin thread-like bars. Inner shell with regular, hexagonal meshes, six times as broad as the bars. About forty radial spines, angular, pyramidal, half as long as the radius of the shell, as broad at the base as the largest mesh.

Dimensions.—Diameter of the outer shell 0.2, of the inner 0.07; outer pores 0.006 to 0.015, inner 0.008; length of the spines 0.05, basal breadth 0.012.

Habitat.—Antarctic Ocean, Station 154, surface.

28. Haliomma wyvillei, Haeckel.

Haliomma wyvillei, Haeckel, 1878, Protistenreich, p. 44, fig. 31. Haliomma species, Wyville Thomson, 1877, Atlantic, vol. i. p. 236, fig. 54.

Cortical shell thin walled, three times as broad as the medullary shell. Both shells with irregular, large, polygonal pores, and very thin bars. From the inner shell arise very numerous (eighty to one hundred and twenty or more) radial spines, which pierce the outer shell, and are outside it, as long as the radius of the inner shell, straight, bristle-shaped, and as thick as the bars.

Dimensions.—Diameter of the outer shell 0.18, of the inner 0.06; pores 0.01 to 0.02, bars 0.001 to 0.002; length of the free spines 0.06.

Habitat.—Central Pacific, Stations 266 to 274, surface.

29. Haliomma beroes, Ehrenberg.

Haliomma beroes, Ehrenberg, 1854, Mikrogeol., Taf. xxxvB. B. iv. fig. 19. Haliomma beroes, Haeckel, 1862, Monogr. d. Radiol., p. 434.

Cortical shell thin walled, three times as broad as the medullary shell, with irregular, roundish pores, twice to four times as broad as the bars. Inner shell with regular, circular pores, twice as broad as the bars. Both shells connected by four (or six ?) radial beams, perpendicularly crossed. Thirty to forty radial spines, conical, thin, shorter than the radius.

Dimensions.—Diameter of the outer shell 0.11, inner 0.04; outer pores 0.007 to 0.012, inner 0.005; length of the spines 0.03, basal breadth 0.005.

Habitat.—Atlantic, depth 2000 fathoms.

30. Haliomma compactum, n. sp. (Pl. 28, figs. 5, 5a).

Cortical shell very thick walled, four times as broad as the thin walled medullary shell; pores of the former irregular, roundish, with high polygonal frames of very different size, twice to four times as broad as the bars. Inner shell with simple, small, polygonal pores, connected with the outer shell by eight (?) regularly disposed thin radial beams, opposite in pairs, prolonged outside into strong conical spines, longer than the radius.

Dimensions.—Diameter of the outer shell 0.08, inner 0.02; outer pores 0.005 to 0.01, inner 0.005; length of the spines 0.06, basal breadth 0.012.

Habitat.—Central Pacific, Stations 265 to 272, depth 2425 to 2925 fathoms.

31. Haliomma permagnum, n. sp.

Cortical shell thick walled, six times as broad as the medullary shell, with irregular, roundish, double-edged pores, three to six times as broad as the bars. Inner shell with regular, circular pores, twice as broad as the bars. One hundred and twenty to one hundred and fifty radial spines, conical, only one-fourth as long as the radius.

Dimensions.—Diameter of the outer shell 0.42, inner 0.07; outer pores 0.012 to 0.025, bars 0.004; inner pores 0.008, bars 0.004; length of the spines 0.05, basal breadth 0.03.

Habitat.—Central Pacific, Station 268, surface.

32. Haliomma patagonicum, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with irregular, roundish pores, twice to three times as broad as the bars. Inner shell also with irregular, roundish pores, of half the size. Forty to fifty radial spines, cylindro-conical, about as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.24, inner 0.06; outer pores 0.012 to 0.02, bars 0.006; inner pores 0.005 to 0.01, bars 0.004; length of the spines 0.3, breadth 0.02.

Habitat.—South-east Pacific, west coast of Patagonia, Station 302, surface.

33. Haliomma clavatum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, with irregular, roundish pores little larger than the bars; eight to twelve on the radius. Inner shell with similar but smaller pores. About twenty radial spines, club-shaped, as long as the radius, three-sided, with prominent edges, twice as broad at the distal end as at the base. (Similar to Acanthosphæra clavata, Pl. 26, fig. 8, but differs from it in the possession of a medullary shell.)

Dimensions.—Diameter of the outer shell 0.2, inner 0.06; outer pores and bars 0.008 to 0.02, inner 0.006 to 0.01; length of the spines 0.1, distal breadth 0.03.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 95. Heliosoma,^[106] Haeckel, 1881, Prodromus, p. 452.

Definition.—Astrosphærida with one medullary (intracapsular) and one cortical (extracapsular) shell, the two being connected by radial beams piercing the central capsule. Shell surface covered with simple radial spines of two different kinds; larger main spines and smaller by-spines.

The genus Heliosoma differs from the preceding Haliomma in the possession of two different kinds of radial spines, and exhibits therefore the same relation to it that Heliosphæra bears to Acanthosphæra among the Coscinommida. The smaller by-spines are much more numerous than the larger main spines.

Subgenus 1. Heliosomantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form.

1. Heliosoma radians, n. sp. (Pl. 28, figs. 3, 3a).

Cortical shell very thin walled, with thread-like bars and regular, hexagonal meshes; twenty to twenty-two on the radius. Medullary shell only one-fifth as large, of the same structure. The two shells connected by twenty very thin radial beams, which are prolonged outside into twenty stout, three-sided pyramidal main spines, as long as the diameter of the inner shell. Between these, arising from the surface, numerous bristle-shaped by-spines.

Dimensions.—Diameter of the outer shell 0.25, inner 0.05, pores 0.012; length of the main spines 0.05, basal breadth 0.012.

Habitat.—Central Pacific, Stations 266 to 274, surface.

2. Heliosoma elegans, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, twice as broad as the bars; ten to twelve on the radius. Medullary shell half as large, with simple, regular, circular pores, twice as broad as the bars. The two shells connected by twenty very thin radial beams, which are prolonged outside into twenty slender, three-sided pyramidal main spines as long as the radius. In each corner of the surface hexagons a bristle-shaped by-spine one-fourth as long.

Dimensions.—Diameter of the outer shell 0.12, inner 0.06; outer pores 0.006, bars 0.003; length of the main spines 0.05, basal breadth 0.01.

Habitat.—Central Pacific, Station 271, surface.

3. Heliosoma echinaster, Haeckel.

Haliomma echinaster, Haeckel, 1862, Monogr. d. Radiol., p. 429, Taf. xxiv. figs. 1-3.

Cortical shell thin walled, with regular, circular, hexagonally framed pores, twice as broad as the bars; ten to twelve on the radius. Medullary shell one-fourth as large, with few irregular, large, polygonal pores and very thin thread-like bars, connected with the former by nine similar thin radial beams, which are prolonged outside into nine pyramidal main spines, as long as the radius. From each corner of the surface hexagon arises a bristle-shaped by-spine, half as long as the main spine.

Dimensions.—Diameter of the outer shell 0.16, inner 0.04; outer pores 0.008, bars 0.004; length of the main spines 0.08, basal breadth 0.01.

Habitat.—Mediterranean (Messina), surface.

4. Heliosoma duodecilla, n. sp.

Cortical shell thick walled, with regular, circular pores, of the same breadth as the bars; sixteen to eighteen on the radius. Medullary shell one-third as large, of the same structure. Twelve radial main spines, regularly disposed, cylindro-conical, longer than the shell diameter, as broad as two pores. Whole surface covered with short conical by-spines.

Dimensions.—Diameter of the outer shell 0.15, inner 0.05; outer pores and bars 0.007; length of the main spines 0.2, breadth 0.02.

Habitat.—South Atlantic, Station 333, surface.

Subgenus 2. Heliosomura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size and form.

5. Heliosoma hastatum, n. sp. (Pl. 28, fig. 4).

Cortical shell very thin walled, with large, irregular, polygonal meshes, three to six times as broad as the bars; four to six on the radius. Medullary shell one-third as large, with small, regular, circular pores. The two shells connected by twelve regularly disposed radial beams, which are prolonged outside into twelve very stout three-sided pyramidal main spines, somewhat longer than the radius, spear-shaped; each of the three wings in the middle part with one tooth. Scattered on the surface numerous by-spines of the same form, half as long and only one-fourth as broad.

Dimensions.—Diameter of the outer shell 0.1, inner 0.033; outer pores 0.006 to 0.013, inner pores 0.002, bars 0.002; length of the main spines 0.06, breadth 0.015.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

6. Heliosoma indicum, n. sp.

Cortical shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars. Medullary shell of the same structure, only one-fourth as large. Thirty to forty conical main spines, as long as the radius; between them numerous bristle-shaped by-spines, only half as long.

Dimensions.—Diameter of the outer shell 0.2, inner 0.05; outer pores 0.004 to 0.01, bars 0.002; length of the main spines 0.1, breadth 0.01.

Habitat.—Indian Ocean, between Aden and Socotora, surface, Haeckel.

Genus 96. Elatomma,^[107] n. gen.

Definition.—Astrosphærida with one medullary (intracapsular) and one cortical (extracapsular) shell, the two being connected by radial beams piercing the central capsule. Shell surface covered with branched radial spines.

The genus Elatomma differs from Haliomma in the ramification of the radial spines, and exhibits therefore the same relation to it that Cladococcus, among the Coscinommida, bears to Acanthosphæra.

Subgenus 1. Elatommella, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form.

1. Elatomma pinetum, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars. From its surface arise twenty to thirty large, three-sided prismatic, radial spines as long as the shell diameter, branched like a pine tree; on each edge of the spine five to six ramified branches, decreasing in size towards the distal end. Similar to Cladococcus pinetum (Pl. 27, figs. 1, 3), but differing in the possession of a medullary shell (one-third as large as the outer), with regular, circular pores, as broad as the bars.

Dimensions.—Diameter of the outer shell 0.2, inner 0.07; cortical pores 0.012, bars 0.004; length of the spines 0.2 to 0.24.

Habitat.—Central Pacific, Stations 266 to 272, surface.

2. Elatomma scoparium, n. sp.

Cortical shell thick walled, with regular, circular pores, twice as broad as the bars, connected with the medullary shell by twenty thin radial beams, which are prolonged outside into twenty large cylindrical radial spines somewhat longer than the radius; in the proximal half simple, in the distal half with six to nine dichotomous, irregular branches. Similar to Cladococcus scoparius (Pl. 27, fig. 2), but much larger, and with a large medullary shell (one-third as broad as the outer), and regular, circular pores.

Dimensions.—Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.01, bars 0.005; length of the spines 0.08.

Habitat.—North Pacific, Station 240, surface.

Subgenus 2. Elatommura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form.

3. Elatomma juniperinum, n. sp. (Pl. 28, fig. 8).

Cortical shell thin walled, with regular, polygonal, or roundish pores, twice to four times as broad as the bars, connected with the small medullary shell by about twenty thin radial beams. Inner shell only one-eighth as broad as the outer, with few irregular, polygonal meshes. Surface covered with very numerous (one hundred to one hundred and fifty or more) branched conical radial spines, one-third as long as the shell radius, with six to twelve short lateral branches.

Dimensions.—Diameter of the outer shell 0.2, inner 0.025; cortical pores 0.08 to 0.016, bars 0.004; length of the spines 0.04.

Habitat.—Central Pacific, Station 271, surface.

4. Elatomma penicillus, n. sp.

Cortical shell thin walled, with irregular, polygonal pores, twice to four times as broad as the bars, connected with the medullary shell by twenty (or more?) very thin beams. These are prolonged outside into twenty straight, three-sided prismatic, radial spines as long as the radius, with a brush-like bunch of six to nine short, irregularly ramified branches at the end. Medullary shell very delicate (half as broad as the outer), with regular, hexagonal meshes and thread-like bars.

Dimensions.—Diameter of the outer shell 0.15, inner 0.08; length of the spines 0.08.

Habitat.—West coast of Norway, Bergen, Haeckel.

5. Elatomma irregulare, n. sp.

Cortical shell thin walled, with irregular, polygonal, or roundish meshes, twice to six times as broad as the bars; the medullary shell of the same structure, half as broad, with smaller irregular pores. Forty to sixty curved, three-sided, radial spines, as long as the shell, with a bunch of very irregular, curved, and partly ramified branches at the distal end.

Dimensions.—Diameter of the outer shell 0.2, inner 0.1; length of the spines 0.2, breadth 0.01.

Habitat.—North Atlantic, Gulf Stream, Færöe Channel, surface, John Murray.

Genus 97. Leptosphæra,^[108] n. gen.

Definition.—Astrosphærida with two extracapsular cortical shells without by-spines, connected by long prismatic radial spines.

The genus Leptosphæra, together with the three following genera, forms the very peculiar and typical small group of Sphæroidea which we call the Diplosphærida (with four genera and twenty-four species); their shell is composed of two concentric spheres as in the three foregoing genera; but whilst in these the inner shell is an intracapsular medullary shell and the outer an extracapsular cortical shell, in the Diplosphærida both shells are extracapsular or cortical shells, therefore the inner shell of the latter corresponds to the outer of the former. The inner spherical shell of all Diplosphærida is composed of very delicate beams and large pores, which are either regular hexagonal or irregular polygonal (never roundish). From its surface arise a variable number (twenty to thirty) of stout long radial spines, which are invariably longer than the shell diameter (often two to three times as long or more), and of three-sided prismatic form, the three edges either smooth or serrate, often with three rows of lateral branches (commonly three to five branches in each row); the latter are invariably of the same form, concavely curved towards the spine, and decrease in size towards the distal end. From the three edges of each main spine in all Diplosphærida, at equal distances from the centre, arise six very thin, thread-like lateral branches (a pair from each edge) and connect the spine in a tangential direction with all neighbouring spines. In this manner the polyhedral outer shell is formed, the meshes of which therefore are always very large and triangular. Sometimes each of these primary triangular meshes becomes filled up with a secondary network, either of regular quadrangular or of irregular polygonal secondary meshes. Besides the constant twenty to thirty large main spines, in the majority of Diplosphærida bristle-shaped radial by-spines arise, either from the inner shell (Diplosphæra) or from the outer (Drymosphæra), or from both (Astrosphæra). They are absent only in Leptosphæra. Commonly the by-spines are simple, rarely forked or branched. The central capsule in the Diplosphærida is usually enclosed in the inner shell; often it completely fills up the latter, or drives out a cæcal protuberance through each mesh; but these processes rarely unite outside. The average size of the Diplosphærida, which are all pelagic organisms, is much larger than that of the other Haliommida.

Subgenus 1. Leptosphærella, Haeckel.

Definition.—Radial spines simple, without lateral branches.

1. Leptosphæra hexagonalis, n. sp. (Pl. 19, fig. 2).

Inner shell with regular, hexagonal meshes, and very thin, thread-like bars; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (Fig. 2 represents the central capsule with numerous club-shaped saccules, prominent externally through the meshes; in the centre a large simple spherical nucleus, one-third as broad as the capsule. The skeleton of this species is identical with that of Diplosphæra hexagonalis, Pl. 19, fig. 3, but has no by-spines.)

Dimensions.—Diameter of the outer shell 0.3, of the inner 0.15.

Habitat.—Cosmopolitan; Mediterranean (Corfu), North Atlantic (Canary Islands), Tropical Pacific, surface.

2. Leptosphæra serrata, n. sp.

Inner shell with regular, hexagonal meshes, five to six times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial spines with three serrated edges (of the same form as the main spines of Drymosphæra dendrophora, Pl. 20, fig. 1).

Dimensions.—Diameter of the outer shell 0.45, of the inner 0.15.

Habitat.—Central Pacific, Station 271, surface.

3. Leptosphæra polygonalis, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (Resembles Drymosphæra polygonalis, Pl. 19, fig. 1, but has no by-spines.)

Dimensions.—Diameter of the outer shell 0.35, inner 0.175.

Habitat.—North Pacific, Station 256, surface.

Subgenus 2. Leptosphæromma, Haeckel.

Definition.—Radial spines with three rows of lateral branches (one row on each edge).

4. Leptosphæra ciliata, n. sp.

Inner shell with regular, hexagonal meshes and very thin thread-like bars; outer shell three times as broad, with simple triangular meshes. Radial spines with smooth edges and three rows of simple, smooth, curved, lateral branches (six branches on each edge), similar to those of Diplosphæra gracilis.

Dimensions.—Diameter of the outer shell 0.6, inner 0.2.

Habitat.—South Atlantic, Station 325, surface.

5. Leptosphæra spinosa, Haeckel.

Diplosphæra spinosa, R. Hertwig, 1879, Organismus d. Radiol., p. 40, Taf. v. fig. 2.

Inner shell with regular, hexagonal meshes, five times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial spines with three densely serrated edges, and with three rows of serrated, simple, curved, lateral branches (three branches on each edge). Differs from the preceding in the thicker bars and the elegantly denticulated spines and branches.

Dimensions.—Diameter of the outer shell 0.66, inner 0.22.

Habitat.—Mediterranean (Messina), R. Hertwig.

6. Leptosphæra stellata, n. sp.

Inner shell with regular, hexagonal meshes, six times as broad as the bars, each bar crossed by a transverse tangential rod, so that each mesh represents an elegant six-rayed star (as in Astrosphæra stellata, Pl. 19, fig. 5, but without radial by-spines); outer shell twice as broad, with simple triangular meshes. Radial spines with serrated edges and three rows of simple lateral branches (four branches on each edge).

Dimensions.—Diameter of the outer shell 0.44, inner 0.22.

Habitat.—Tropical Atlantic (Ascension Island), Station 343, surface.

7. Leptosphæra reticulum, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell four times as broad, also with irregular, polygonal meshes, the sides of the triangular main meshes being connected by irregular lateral ramules, forming an extremely delicate reticulum.

Dimensions.—Diameter of the outer shell 0.64, inner 0.16.

Habitat.—South Pacific, Station 291, surface.

Genus 98. Diplosphæra,^[109] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 804.

Definition.—Astrosphærida with two extracapsular cortical shells, connected by long, prismatic, radial spines; inner shell with thin radial by-spines.

The genus Diplosphæra differs from its ancestral form Leptosphæra in the development of radial by-spines on the surface of the inner shell, the outer shell being smooth.

Subgenus 1. Diplosphærella, Haeckel.

Definition.—Radial main spines simple, without lateral branches.

1. Diplosphæra hexagonalis, n. sp. (Pl. 19, fig. 3).

Inner shell with regular, hexagonal meshes and very thin thread-like bars; at each nodal-point one bristle-shaped by-spine; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (The radially striped central capsule, enclosed in the inner shell, envelops a large central nucleus one-third its size, fig. 3.)

Dimensions.—Diameter of the outer shell 0.36, inner 0.18.

Habitat.—Central Pacific, Stations 265 to 274, surface.

2. Diplosphæra ornata, n. sp.

Inner shell with regular, hexagonal meshes, four times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial main spines as well as the bars of both shells very elegantly denticulated; radial by-spines (very numerous in the surface of the inner shell) smooth.

Dimensions.—Diameter of the outer shell 0.7, inner 0.24.

Habitat.—Indian Ocean, Madagascar, surface, Rabbe.

3. Diplosphæra dictyota, n. sp.

Inner shell with regular, hexagonal meshes, six times as broad as the bars; at each nodal-point one radial by-spine; outer shell two and a half times as broad, with very delicate square meshes, separated by thread-like bars which arise from the sides of the triangular main meshes. Radial main spines with three serrated edges. (Differs from the similar Diplosphæra gracilis in the simple main spines, with delicate dentition of the edges.)

Dimensions.—Diameter of the outer shell 0.5, inner 0.2.

Habitat.—North Atlantic, Canary Islands, surface.

4. Diplosphæra polygonalis, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars, covered with very numerous bristle-shaped by-spines; outer shell twice as broad, with simple triangular meshes. Radial main spines with three smooth edges.

Dimensions.—Diameter of the outer shell 0.44, inner 0.22.

Habitat.—South Pacific, Station 288, surface.

Subgenus 2. Diplosphæromma, Haeckel.

Definition.—Radial main spines with three rows of lateral branches (one row on each edge).

5. Diplosphæra gracilis, Haeckel.

Diplosphæra gracilis, Haeckel, 1862, Monogr. d. Radiol., p. 354, Taf. x. fig. 1.

Inner shell with regular, hexagonal meshes and very thin bars; at each nodal-point one simple bristle-shaped radial by-spine; outer shell twice as broad, with very delicate square meshes, separated by thread-like bars which arise from the sides of the triangular main meshes. Radial spines with smooth edges and with three rows of simple curved lateral branches (four to six branches on each edge).

Dimensions.—Diameter of the outer shell 0.54, inner 0.27.

Habitat.—Mediterranean (Messina).

6. Diplosphæra denticulata, n. sp.

Inner shell with regular, hexagonal meshes, four times as broad as the bars; at each nodal-point is a simple bristle-shaped by-spine; outer shell three times as broad, with simple triangular meshes. Radial spines very strong, with dentated edges and with three rows of lateral branches (six dentated curved branches on each edge).

Dimensions.—Diameter of the outer shell 0.4, inner 0.13.

Habitat.—North Atlantic, Azores, surface.

7. Diplosphæra reticulata, n. sp.

Inner shell with regular, hexagonal meshes, five times as broad as the bars, which are densely covered with very numerous, simple bristle-shaped by-spines; outer shell four times as broad, with very numerous small irregular polygonal meshes, forming a very delicate network, and filling out the large triangular main meshes. Radial spines with three serrated edges and three rows of short curved branches (four to five branches on each edge).

Dimensions.—Diameter of the outer shell 0.6, inner 0.15.

Habitat.—North Atlantic, Gulf Stream, Færöe Channel, surface, John Murray.

8. Diplosphæra triglochin, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell three times as broad, with similar irregular polygonal meshes, filling out the large triangular main meshes. Radial spines with three serrated edges, each of which bears one single large lateral branch, concavely curved towards the distal end. By-spines of the inner shell very numerous.

Dimensions.—Diameter of the outer shell 0.5, inner 0.17.

Habitat.—Central Pacific, Station 264, surface.

Genus 99. Drymosphæra,^[110] Haeckel, 1881, Prodromus, p. 452.

Definition.—Astrosphærida with two extracapsular cortical shells, connected by long prismatic, radial spines; outer shell with thin radial by-spines.

The genus Drymosphæra differs from its ancestral form Leptosphæra in the development of radial by-spines on the surface of the outer shell, the inner shell being smooth.

Subgenus 1. Drymosphærella, Haeckel.

Definition.—Radial by-spines simple, not branched (main spines simple).

1. Drymosphæra hexagonalis, n. sp.

Inner shell with regular, hexagonal meshes and very thin thread-like bars; outer shell twice as broad, with simple triangular meshes and thin thread-like bars, which bear very numerous, bristle-shaped radial by-spines. Radial main spines with three smooth edges. (Differs from the first species of the other three genera of Diplosphærida in the presence of by-spines on the outer, and their absence on the inner shell.)

Dimensions.—Diameter of the outer shell 0.32, inner 0.16.

Habitat.—Central Pacific, Station 274, surface.

2. Drymosphæra polygonalis, n. sp. (Pl. 19, fig. 1).

Diplosphæra polygonalis, Haeckel, 1879, Atlas.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell one and a half times as broad, with simple triangular meshes and thicker bars, which bear numerous bristle-shaped radial by-spines (in the figure the majority of these are broken off). Radial main spines with three smooth edges. (Similar to Leptosphæra polygonalis and Diplosphæra polygonalis, but differs from both in the presence of by-spines on the outer, and their absence on the inner shell.)

Dimensions.—Diameter of the outer shell 0.33, inner 0.22.

Habitat.—North Pacific, Station 236 south of Japan, surface.

Subgenus 2. Drymosphæromma, Haeckel.

Definition.—Radial by-spines forked or branched (main spines simple).

3. Drymosphæra furcata, n. sp.

Inner shell with irregular, polygonal meshes and thin bars, the former five times as broad as the latter; outer shell two and a half times as broad, with simple triangular meshes and smooth bars, bearing numerous long smooth bristle-shaped by-spines, which in the distal half are forked. Radial main spines with three smooth edges.

Dimensions.—Diameter of the outer shell 0.4, inner 0.16.

Habitat.—Indian Ocean, Ceylon, surface, Haeckel.

4. Drymosphæra cladophora, n. sp.

Inner shell with irregular, polygonal meshes, three to six times as broad as the smooth bars; outer shell twice as broad, with simple triangular meshes and very thin smooth bars, bearing numerous curved, irregularly branched, smooth by-spines. Radial main spines with three serrated edges.

Dimensions.—Diameter of the outer shell 0.4, inner 0.2.

Habitat.—Central Pacific, Station 276, surface.

5. Drymosphæra dendrophora, n. sp. (Pl. 20, figs. 1, 1a, 1b).

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell one and a half times as broad, with simple triangular meshes and thicker bars, which bear a forest of very numerous, repeatedly dichotomous or irregularly branched, curved by-spines, longer than the diameter of the outer shell. Radial main spines with three dentated edges. All parts of the skeleton, the net bars as well as the radial beams and spines, are very elegantly denticulated (fig. 1b). The central capsule (fig. 1a) completely distends the inner shell and forces out protuberances through all its pores; in its centre lies a nucleus one-third its size.

Dimensions.—Diameter of the outer shell 0.25, inner 0.16.

Habitat.—Central Pacific, Station 271, surface.

Genus 100. Astrosphæra,^[111] n. gen.

Definition.—Astrosphærida with two extracapsular cortical shells, connected by long, prismatic, radial spines; inner and outer shell with thin radial by-spines.

The genus Astrosphæra differs from its ancestral form, Leptosphæra, in the development of radial by-spines on the surface of both shells.

Subgenus 1. Astrosphærella, Haeckel.

Definition.—Radial main spines simple without lateral branches.

1. Astrosphæra hexagonalis, n. sp. (Pl. 19, fig. 4).

Inner shell with regular, hexagonal meshes and very thin bars, having a bristle-shaped, short radial by-spine in each hexagon-corner; outer shell twice as broad, with simple triangular meshes and thicker bars, bearing one row of simple bristle-shaped, curved, radial by-spines. Radial main spines with three smooth edges.

Dimensions.—Diameter of the outer shell 0.32, inner 0.16.

Habitat.—South Pacific (West Patagonia), Station 302, surface.

2. Astrosphæra splendens, n. sp.

Inner shell with regular, hexagonal meshes, four times as broad as the bars, and covered with numerous curved, long, bristle-shaped by-spines; outer shell three times as broad, with simple triangular meshes and thin bars, bearing a row of very long, curved, bristle-shaped by-spines. Radial main spines with three dentated edges. All parts of the skeleton elegantly denticulated, as in Drymosphæra dendrophora (Pl. 20, fig. 1).

Dimensions.—Diameter of outer shell 0.7, inner 0.24.

Habitat.—Tropical Atlantic, Station 347, surface.

Subgenus 2. Astrosphæromma.

Definition.—Radial main spines with three rows of lateral branches (one row on each edge).

3. Astrosphæra sideræa, n. sp.

Inner shell with regular, hexagonal meshes, six times as broad as the bars, and covered with numerous short bristle-shaped by-spines; outer shell four times as broad, with simple triangular meshes, and rows of long bristle-shaped by-spines arising from the bars. Radial main spines with three serrated edges and three rows of lateral branches (four branches on each edge).

Dimensions.—Diameter of the outer shell 0.6, inner 0.15.

Habitat.—Central Pacific, Station 266, surface.

4. Astrosphæra stellata, n. sp. (Pl. 19, fig. 5).

Diplosphæra stellata, Haeckel, 1881, Prodrom. et Atlas.

Inner shell with regular, hexagonal, six-rayed meshes, each bar being crossed by a transverse tangential rod, at each nodal-point a long bristle-shaped by-spine; outer shell three times as broad, with simple triangular meshes and denticulated thin bars, bearing a row of bristle-shaped radial by-spines. Radial main spines in the proximal half with three serrated edges, in the distal half with three rows of curved lateral branches (five branches on each edge).

Dimensions.—Diameter of the outer shell 0.6, inner 0.2.

Habitat.—Central Pacific, Station 274, surface.

Subfamily Actinommida,^[112] Haeckel, 1862, Monogr. d. Radiol., p. 440 (sensu emendato).

Definition.—Astrosphærida with three concentric, spherical, lattice-shells, united by radial beams.

Genus 101. Actinomma,^[113] Haeckel, 1862, Monogr. d. Radiol., p. 440.

Definition.—Astrosphærida with three concentric lattice-spheres and numerous simple radial spines of one kind.

The genus Actinomma is here restricted to those Sphæroidea which combine the possession of three concentric lattice-shells with numerous radial spines on the surface; the spines are all simple, being of one and the same kind. Commonly two of the three shells are intracapsular medullary shells, connected by radial beams (piercing the central capsule) with the outer, extracapsular, cortical shell. But in some species only one medullary shell is enclosed in the central capsule, whilst both other shells lie outside it. In such case the distance between these two cortical shells is much smaller than their distance from the simple internal medullary shell. These forms correspond more to aculeate Rhodosphæræ, whilst the others resemble aculeate Thecosphæræ.

Subgenus 1. Actinommantha, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form; spines on the entire surface (commonly one spine at each nodal-point).

1. Actinomma hexagonium, n. sp.

Cortical shell, as well as both medullary shells, very thin walled, with regular, hexagonal pores and thread-like bars between them. Pores of the outer shell twice as broad as those of the middle, and three times as broad as those of the inner shells. Radial proportion of the three spheres = 1 : 3 : 9; about twenty thin radial beams between them. At each nodal-point of the surface arises one bristle-shaped radial spine, half as long as the radius.

Dimensions.—Diameter of the outer shell 0.22, middle 0.07, inner 0.025; meshes of the cortical shell 0.01; length of the spines 0.05.

Habitat.—Central Pacific, Stations 270 to 274, surface.

2. Actinomma facetum, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars. Pores of both medullary shells regular, circular. Radial proportion of the three spheres = 1 : 2 : 4; about forty thin radial beams between them. At each nodal-point of the surface arises one short, three-sided pyramidal, radial spine, about one-third as long as the radius.

Dimensions.—Diameter of the outer shell 0.16, middle 0.08, inner 0.04; cortical pores 0.012, bars 0.004; length of the spines 0.03, basal breadth 0.015.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Actinomma anthomma, n. sp.

Cortical shell thick walled, with regular, six-lobed pores, twice as broad as the bars. At each nodal-point of the surface is one short conical radial spine, as long as the diameter of the pores; one corresponding to each lobe, and there is therefore around each pore a regular corona of six spines, as in Haliomma lirianthus (Pl. 28, fig. 1b). Both medullary shells with simple, circular, regular pores. Radial proportion of the three spheres = 1 : 2.5 : 7; radial beams between them only six, opposite in pairs in the three dimensive axes.

Dimensions.—Diameter of the outer shell 0.2, middle 0.075, inner 0.003; cortical pores 0.01, bars 0.005; length of the spines 0.01.

Habitat.—Central Pacific, Station 271, surface.

4. Actinomma castanomma, n. sp.

Cortical shell as well as both medullary shells thick walled, with regular, circular pores, twice as broad as the bars; between them at each nodal-point one bristle-shaped radial spine, one-third as long as the radius, with conical base. Radial proportion of the three spheres = 2 : 3 : 8; only six radial beams between them (opposed in pairs in the three dimensive axes).

Dimensions.—Diameter of the outer shell 0.15, middle 0.06, inner 0.04; cortical pores 0.008, bars 0.004; length of the spines 0.025.

Habitat.—South Atlantic, Station 333, surface.

5. Actinomma entactinia, Stöhr.

Actinomma entactinia, Stöhr, 1880, Palæontogr., vol. xxvi. p. 93, Taf. ii. fig. 12.

Cortical shell as well as both medullary shells thick walled, with regular, circular pores, of the same breadth as the bars. Radial proportion of the three spheres = 1 : 3 : 8; radial beams between them very numerous (thirty to fifty or more?). Entire surface covered with short thick conical spines, only one-fifth as long as the radius.

Dimensions.—Diameter of the outer shell 0.16, middle 0.06, inner 0.02; cortical pores and bars 0.007; length of the spines 0.015.

Habitat.—Fossil in the Tertiary rocks of Sicily, Grotte, Caltanisetta.

Subgenus 2. Actinommetta, Haeckel.

Definition.—Pores of the outer shell regular, of nearly equal size and similar form; spines not over the entire surface, but scattered at intervals (their number smaller than that of the nodal-points).

6. Actinomma japonicum, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars. Both medullary shells with simple, circular, regular pores, of the same breadth as the bars. Radial proportion of the three spheres = 2 : 5 : 9; radial beams between them twenty, prolonged outside into twenty symmetrically disposed, three-sided pyramidal spines, as long as the radius.

Dimensions.—Diameter of the outer shell 0.18, middle 0.1, inner 0.04; cortical pores 0.01, bars 0.003; length of the spines 0.1, basal breadth 0.012.

Habitat.—North Pacific, Station 240, east of Japan, surface.

7. Actinomma denticulatum, n. sp. (Pl. 29, fig. 3).

Cortical shell thick walled, with regular, circular, double-edged pores, twice as broad as the bars. Forty to fifty radial spines, three-sided pyramidal, half as long as the radius, with three elegantly denticulated edges. Radial proportion of the three spheres = 1 : 2 : 5. (Differs from Haliomma denticulatum only in the double medullary shell and larger size.)

Dimensions.—Diameter of the outer shell 0.14, middle 0.06, inner 0.03; cortical pores 0.01, bars 0.005; length of the spines 0.04, basal breadth 0.01.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

8. Actinomma trinacrium, Haeckel.

Actinomma trinacrium, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiv. figs. 6-8. Haliomma trinacrium, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 815.

Cortical shell as well as both medullary shells thin walled, with subregular, circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9; radial beams between them twenty, prolonged outside into strong, three-sided pyramidal spines, as long as the radius; between them, on the surface, numerous similar spines. Sometimes the latter remain smaller, the pores more irregular, and then this species corresponds to Echinomma trinacrium.

Dimensions.—Diameter of the outer shell 0.09, middle 0.03, inner 0.01; cortical pores 0.008, bars 0.004; length of the spines 0.04, basal breadth 0.01.

Habitat.—Mediterranean (Messina, Corfu, Haeckel), surface.

9. Actinomma pachyderma, n. sp. (Pl. 29, figs. 4, 5).

Cortical shell very thick walled, with regular, circular, double-edged pores, twice as broad as the bars. Both medullary shells with simple, small, circular pores, of the same breadth as the bars. Radial proportion of the three spheres = 1 : 2 : 4; radial spines about twenty, conical, shorter than the radius, prolonged inside into twenty very thin connecting beams (fig. 4).

Dimensions.—Diameter of the outer shell 0.08, middle 0.04, inner 0.02; cortical pores 0.01; bars 0.005; length of the spines 0.03, basal breadth 0.01.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

Subgenus 3. Actinommilla, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size and form; spines over the entire surface (commonly one spine at each nodal-point).

10. Actinomma spinigerum, Stöhr.

Actinomma spinigerum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 92, Taf. ii. fig. 10.

Cortical shell thick walled, with irregular, roundish, or subcircular pores, twice to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 8; between them eight (?) connecting radial beams. Entire surface densely covered with small conical spines, not larger than the pores.

Dimensions.—Diameter of the outer shell 0.17, middle 0.07, inner 0.023; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.01.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.

11. Actinomma hirsutum, n. sp.

Cortical shell thick walled, with irregular, roundish pores, about the same breadth as the bars. Radial proportion of the three spheres = 1 : 2 : 8; between them numerous (twenty to thirty or more) cylindrical connecting beams. Entire surface densely covered with innumerable small bristle-shaped spines, as long as the diameter of the inner shell.

Dimensions.—Diameter of the outer shell 0.25, middle 0.06, inner 0.03; cortical pores and bars 0.004 to 0.008; length of the spines 0.03.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 4. Actinommura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size and form; spines not over the entire surface, but scattered at intervals (their number smaller than that of the nodal-points).

12. Actinomma capillaceum, n. sp. (Pl. 29, fig. 6).

Cortical shell very thin walled, with irregular, polygonal meshes (sixteen to eighteen on the radius), three to six times as broad as the bars. Both medullary shells with smaller pores of the same structure. Radial proportion of the three spheres = 1 : 2.5 : 7; radial connecting beams between them very thin and numerous (one hundred and twenty to one hundred and fifty or more), each prolonged outside into a short three-sided pyramidal spine, as long as the radius of the inner shell. (Similar to Haliomma capillaceum.)

Dimensions.—Diameter of the outer shell 0.27, middle 0.1, inner 0.04; cortical pores 0.01 to 0.02, bars 0.003; length of the spines 0.02, basal breadth 0.005.

Habitat.—Central Pacific, Stations 266 to 274, surface.

13. Actinomma arcadophorum, n. sp. (Pl. 29, figs. 7, 8).

Cortical shell very thin walled, with irregular, polygonal meshes, ten to twenty times as broad as the bars; twelve to sixteen on the radius. Both medullary shells with similar delicate network. Radial proportion of the three spheres = 1 : 2 : 6; numerous thin radial beams (forty to eighty or more) connect both medullary shells and alternate with other beams, which arise from arcade-shaped protuberances of the outer medullary shell, and connect it with the cortical shell. Outer prolongations of these form the bristle-shaped spines of the surface.

Dimensions.—Diameter of the outer shell 0.22, middle 0.09, inner 0.04; cortical pores 0.01 to 0.02, bars 0.001 to 0.002; length of the radial spines 0.2.

Habitat.—Central Pacific, Station 266, surface.

14. Actinomma schwageri, Stöhr.

Actinomma schwageri, Stöhr, 1880, Palæontogr., vol. xxvi. p. 92, Taf. ii. fig. 9a, b.

Cortical shell thick walled, with irregular, large, polygonal meshes, five to twelve times as broad as the bars; six to eight on the radius. Both medullary shells with very small, circular, regular pores. Radial proportion of the three spheres = 1 : 2 : 9; connecting radial beams between them nine, prolonged outside into nine short stout, three-sided pyramidal spines, as long as the diameter of the inner shell.

Dimensions.—Diameter of the outer shell 0.17, middle 0.04, inner 0.02; cortical pores 0.01 to 0.03, bars 0.006 and less; length of the spines 0.02, basal breadth 0.01.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.

15. Actinomma dodecomma, n. sp.

Cortical shell thin walled, with irregular, roundish pores, three to six times as broad as the bars. Both medullary shells with regular, circular pores, twice as broad as the bars. Radial proportion of the three shells = 1 : 2.5 : 7; connecting radial beams between them twelve, regularly disposed, prolonged outside into twelve strong, three-sided pyramidal spines, as long as the radius.

Dimensions.—Diameter of the outer shell 0.14, middle 0.05, inner 0.02; cortical pores 0.008 to 0.018, bars 0.003; length of the spines 0.08, breadth 0.02.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

16. Actinomma pachycapsa, n. sp.

Cortical shell very thick walled, with irregular, roundish pores, twice to four times as broad as the bars; twelve to sixteen on the radius. Radial proportion of the three spheres = 1 : 3 : 12. Both medullary shells of similar irregular structure, connected with the cortical shell by twelve regularly disposed radial beams, which are prolonged outside into twelve short stout conical spines, as long as the diameter of the middle shell.

Dimensions.—Diameter of the outer shell 0.25, middle 0.06, inner 0.02; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

17. Actinomma giganteum, n. sp.

Cortical shell thick walled, little larger than the outer medullary shell, whilst the inner is only one-tenth as large. Pores of all three shells irregular, roundish, or subcircular, twice to three times as broad as the bars, on an average twice as large in the outer and middle as in the inner shell. Sixty to eighty short conical radial spines on the surface, about as long as the diameter of the inner shell, and one-fourth as broad at the base. Radial proportion of the three spheres = 1 : 9 : 10.

Dimensions.—Diameter of the outer shell 0.4 to 0.5, middle 0.35 to 0.45, inner 0.05 to 0.06.

Habitat.—Fossil in Barbados.

Genus 102. Echinomma,^[114] Haeckel, 1881, Prodromus, p. 453.

Definition.—Astrosphærida with three concentric lattice-spheres and numerous simple radial spines of two different kinds; larger main spines and smaller by-spines.

The genus Echinomma, differs from its ancestral form, Actinomma, in the differentiation of the radial spines. Whilst a large number of small by-spines cover the entire surface, a smaller number of large main spines are scattered over it, or limited to certain regularly distributed points. It represents Heliosoma among the Haliommida.

Subgenus 1. Echinommetta, Haeckel.

Definition.—Pores of the cortical shell regular, of nearly equal size and similar form.

1. Echinomma echinidium, n. sp.

Cortical shell thin walled, with regular, hexagonal pores, four times as broad as the bars; ten to twelve on the radius. Both medullary shells with regular, circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 5. Surface covered with short bristle-shaped by-spines (one in every hexagon-corner); twenty main spines regularly disposed, three-sided pyramidal, as long as the diameter of the inner shell.

Dimensions.—Diameter of the outer shell 0.1, middle 0.045, inner 0.02; cortical pores 0.008, bars 0.002; length of the main spines 0.02, breadth 0.01.

Habitat.—South Pacific, Station 295, surface.

2. Echinomma cidaris, n. sp.

Cortical shell thin walled, with regular, circular, hexagonally framed pores, twice as broad as the bars; six to eight on the radius. Both medullary shells with simple, circular pores. Radial proportion of the three spheres = 1 : 2 : 6. Surface covered with short bristle-shaped by-spines, half as long as the forty to fifty main spines, which are three-sided pyramidal, and reach the radius of the shell.

Dimensions.—Diameter of the outer shell 0.18, middle 0.06, inner 0.03; cortical pores 0.01, bars 0.005; length of the main spines 0.08, basal breadth 0.015.

Habitat.—Central Pacific, Station 272, surface.

3. Echinomma aculeatum, Haeckel.

Actinomma aculeatum, Stöhr, 1880 Palæontogr., vol. xxvi. p. 92, Taf. ii. fig. 11.

Cortical shell thick walled with regular circular pores, of the same breadth as the bars; eight to ten on the radius. Radial proportion of the three spheres = 1 : 2 : 8. Surface covered with short conical by-spines about twenty strong main spines, three-sided pyramidal, one-third as long as the shell diameter.

Dimensions.—Diameter of the outer shell 0.16, middle 0.04, inner 0.02; cortical pores and bars 0.003; length of the main spines 0.05, basal breadth 0.013.

Habitat.—Fossil in the Tertiary rocks of Sicily and Barbados; living in the Atlantic, Station 332, depth 2200 fathoms.

4. Echinomma diadema, n. sp.

Cortical shell thick walled with regular circular pores, twice as broad as the bars; sixteen to eighteen on the radius. Radial proportion of the three spheres = 1 : 3 : 11. Surface covered with short bristle-shaped by-spines one third as long as the twelve stout conical main spines, which reach in length the radius, and lie opposite in pairs in six axes.

Dimensions.—Diameter of the outer shell 0.22, middle 0.06, inner 0.02; cortical pores 0.006, bars 0.003 length of the main spines 0.12, basal breadth 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subgenus 2. Echinommura, Haeckel.

Definition.—Pores of the cortical shell irregular, of different size or form.

5. Echinomma sphærechinus, n. sp. (Pl. 29, fig. 2).

Actinomma sphærechinus, Haeckel, 1879, Atlas (pl. xxix. fig. 2).

Cortical shell thin walled, with irregular, roundish pores, twice to five times as broad as the bars; five to seven on the radius. Both medullary shells with regular, circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Surface covered with thirty to fifty pyramidal main spines, as long as the diameter of the inner shell, and with numerous small conical by-spines of half the length.

Dimensions.—Diameter of the outer shell 0.11, middle 0.05, inner 0.025; cortical pores 0.01 to 0.02, bars 0.004; length of the main spines 0.03, basal breadth 0.005.

Habitat.—North Atlantic, Station 353, surface.

6. Echinomma trinacrium, Haeckel.

Actinomma trinacrium, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiv. figs. 6-8.

Cortical shell thin walled, with irregular, roundish pores, twice to three times as broad as the bars. Both medullary shells with regular, circular pores. Radial proportion of the three spheres = 1 : 3 : 9. On the surface about twenty three-sided pyramidal main spines, as long as the radius, and numerous (forty to sixty) by-spines of half the length. (Compare with this species Actinomma trinacrium, with which it is connected by transitional forms.)

Dimensions.—Diameter of the outer shell 0.09, middle 0.03, inner 0.01; cortical pores 0.008 to 0.012, bars 0.004; length of the spines 0.02 to 0.05, basal breadth 0.01.

Habitat.—Mediterranean (Messina).

7. Echinomma toxopneustes, n. sp. (Pl. 29, fig. 1).

Cortical shell thin walled, with large, irregular roundish, polygonally framed pores, twice to four times as broad as the crested bars. Both medullary shells of similar structure. Radial proportion of the three spheres = 1 : 2.5 : 6. Numerous (thirty to fifty or more) thin radial beams connecting them, prolonged outside into strong three-sided pyramidal spines, shorter than the radius; each of the three wings with two teeth. Between these, numerous smaller angular by-spines of one-quarter to one-half the length.

Dimensions.—Diameter of the outer shell 0.12, middle 0.05, inner 0.02; cortical pores 0.01 to 0.03, bars 0.008; length of the main spines 0.05, basal breadth 0.01.

Habitat.—South-east Pacific (South of Juan Fernandez), Station 300, surface.

Genus 103. Pityomma,^[115] Haeckel, 1881, Prodromus, p. 453.

Definition.—Astrosphærida with three concentric lattice-shells and numerous branched radial spines.

The genus Pityomma differs from its ancestral form, Actinomma, in the ramification of its radial spines, and exhibits therefore the same relation to it that Elatomma, among the Haliommida, bears to Haliomma.

1. Pityomma scoparium, n. sp.

Cortical shell thick walled, connected with both concentric medullary shells by twenty thin radial beams, which are prolonged outside into twenty large cylindrical radial spines; these are somewhat shorter than the shell radius, simple in the proximal inner half, irregularly branched in the outer half. All three spheres with regular, circular pores, twice to three times as broad as the bars; radial proportion = 1 : 2 : 6. (Similar to Cladococcus scoparius, Pl. 27, fig. 2, and Elatomma scoparium, but differs from both in the double medullary shell.)

Dimensions.—Diameter of the outer shell 0.15, middle 0.05, inner 0.025; length of the spines 0.1.

Habitat.—Central Pacific, Station 273, surface.

2. Pityomma piniferum, n. sp.

Cortical shell thin walled, with irregular, roundish pores, connected with both medullary shells by twenty stout radial beams, which are prolonged outside into twenty large three-sided prismatic spines. These are longer than the shell diameter and have three dentate edges, being branched like a pine tree (with four to six ramified branches on each edge, decreasing in size towards the distal end); similar to those of Cladococcus abietinus (Pl. 27, fig. 3). Radial proportion of the three spheres = 1 : 2 : 8. Both medullary shells with regular, circular pores, twice as broad as the bars.

Dimensions.—Diameter of the outer shell 0.2, middle 0.05, inner 0.025; length of the spines 0.25.

Habitat.—South Pacific, Station 299 (Juan Fernandez), surface.

3. Pityomma drymodes, n. sp. (Pl. 29, fig. 9).

Cortical shell thin walled, connected with both medullary shells by very numerous (one hundred to two hundred or more) very thin radial beams, which are prolonged outside into thin branched radial spines, scarcely half as long as the shell radius, each spine bearing six to nine simple branches. Outer and middle shell uneven, with hill-shaped protuberances and valleys between them; the connecting radial beams, which arise from the top of the protuberances of the middle shell, are inserted into the deepest part of the valleys of the outer shell. Radial proportion of the three spheres = 1 : 3 : 8. Outer medullary shell with small, irregular, roundish, or polygonal pores, not much broader than the bars; innermost shell with polygonal pores and very thin bars.

Dimensions.—Diameter of the outer shell 0.28, middle 0.1, inner 0.033; length of the spines 0.07, breadth 0.004.

Habitat.—Central Pacific, Station 271, surface.

Subfamily Cromyommida,^[116] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.—Astrosphærida with four concentric spherical lattice-shells.

Genus 104. Cromyomma,^[117] Haeckel, 1881, Prodromus, p. 454.

Definition.—Astrosphærida with four concentric lattice-spheres and numerous simple radial spines of one kind.

The genus Cromyomma is the common ancestral form of the Cromyommida, or of those Astrosphærida in which the shell is composed of four concentric spheres, connected by radial beams. Usually two of these are intracapsular or medullary shells, two extracapsular or cortical shells; the distance between the former and the latter is greater than the distance between either the two inner or the two outer shells. In some cases, however (e.g., Cromyomma zonaster), the distance between all four shells is equal.

Subgenus 1. Cromyommetta, Haeckel.

Definition.—Pores of the outer cortical shell regular, of nearly equal size and similar form.

1. Cromyomma villosum, n. sp. (Pl. 30, fig. 2).

Radial proportion of the four spheres = 1 : 2 : 4 : 5. Outer cortical shell thick walled, densely covered with innumerable bristle-shaped radial spines, half as long as the radius. Pores regular, circular, double-edged, of the same breadth as the bars; ten to twelve on the radius. The thick outer shell is so dark, that the outlines only of the other three shells can be seen.

Dimensions.—Diameter of the four shells—(A) outer cortical shell 0.2, (B) inner cortical shell 0.16, (C) outer medullary shell 0.08, (D) inner medullary shell 0.04; pores and bars of the outer shell 0.008; length of the spines 0.04.

Habitat.—Central Pacific, Station 267, depth 2700 fathoms.

2. Cromyomma zonaster, Haeckel.

Acanthosphæra zonaster, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ii. fig. 2.

Radial proportion of the four spheres = 2 : 3 : 4 : 5. Outer cortical shell thick walled, densely covered with numerous bristle-shaped radial spines, as long as the radius. Pores regular, circular, twice as broad as the bars; eight to ten on the radius. The thick outer shell is so dark, that the outlines only of the other three shells can be seen.

Dimensions.—Diameter of the four shells—(A) 0.15, (B) 0.12, (C) 0.09, (D) 0.06; pores of the outer shell 0.01, bars 0.005; length of the spines 0.08.

Habitat.—Arctic Ocean, Greenland (depth 1000 fathoms), "Alert" Expedition.

3. Cromyomma perplexum, Stöhr.

Cromyomma perplexum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 95, Taf. iii. fig. 5.

Radial proportion of the four spheres = 1 : 2 : 3 : 4. Outer cortical shell thick walled, densely covered with short conical spines, as long as the diameter of the pores. These are regular, circular, three times as broad as the bars; six to eight on the radius. The thick outer shell is so dark, that the outlines only of the three other shells can be seen.

Dimensions.—Diameter of the four shells—(A) 0.17, (B) 0.13, (C) 0.087, (D) 0.043; pores of the outer shell 0.015, bars 0.005; length of the spines 0.02.

Habitat.—Fossil in the Tertiary rocks of Sicily (Grotte) Stöhr.

Subgenus 2. Cromyommura, Haeckel.

Definition.—Pores of the outer cortical shell irregular, of different size and form.

4. Cromyomma perspicuum, n. sp. (Pl. 30, fig. 8).

Cromyosphæra perspicua, Haeckel, 1879, Atlas (pl. xxx. fig. 8).

Radial proportion of the four shells = 1 : 2.5 : 6 : 9. Outer cortical shell very thin walled, with thread-like bars, and irregular, polygonal pores; inner cortical shell with similar pores, but with thicker bars. Both medullary shells with regular, circular pores (the outer three times as broad as the inner). Numerous thin radial beams connect the latter with the former; other very thin and numerous beams connect the two cortical shells, and are prolonged outside into short bristle-shaped spines (often longer than in the figure).

Dimensions.—Diameter of the four shells—(A) 0.18, (B) 0.12, (C) 0.05, (D) 0.02; pores of the outer shell 0.01 to 0.02; length of the spines 0.01 to 0.03.

Habitat.—Central Pacific, Station 274, surface.

5. Cromyomma quadruplex, Haeckel.

Cromyomma quadruplex, Haeckel, 1862, Monogr. d. Radiol., p. 446. Haliomma quadruplex, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 243.

Radial proportion of the four spheres = 1 : 3 : 7 : 10. Outer cortical shell thin walled, irregularly covered with numerous angular spines, as long as the radius. Pores of all four shells irregular, roundish, increasing in size from the first to the fourth.

Dimensions.—Diameter of the four shells—(A) 0.15, (B) 0.1, (C) 0.045, (D) 0.015; pores of the outer shell 0.01 to 0.02; length of the spines 0.07.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

6. Cromyomma macroporum, Stöhr.

Cromyomma macroporum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 95, Taf. iii. fig. 4.

Radial proportion of the four spheres = 1 : 3 : 6 : 9. Outer cortical shell thick walled, densely covered with short conical spines, as long as the diameter of the pores; the latter are irregular, roundish, or polygonal, larger and smaller alternating.

Dimensions.—Diameter of the four shells—(A) 0.1, (B) 0.066, (C) 0.033, (D) 0.011; pores of the outer shell 0.033 to 0.016, bars 0.003; length of the spines 0.01.

Habitat.—Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.

7. Cromyomma circumtextum, n. sp. (Pl. 30, fig. 4).

Radial proportion of the four spheres = 1 : 2 : 5 : 7. Outer cortical shell very delicate and thin walled, with thread-like bars and large, irregular, polygonal meshes (larger than the innermost shell); inner cortical shell also with irregular, polygonal pores, three to nine times as broad as the thick bars. Both medullary shells with subregular, circular pores (the outer three times as broad as the inner). Radial spines twelve to twenty, three-sided prismatic, stout, piercing the three outer shells, inserted on the innermost; their outer part pyramidal, half as long as the radius.

Dimensions.—Diameter of the four shells—(A) 0.22, (B) 0.15, (C) 0.07, (D) 0.03; meshes of the outer shell 0.02 to 0.04; length of the outer spines 0.05.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

8. Cromyomma mucronatum, n. sp. (Pl. 30, figs. 5, 5a).

Radial proportion of the three spheres = 1 : 2 : 3 : 6. Outer cortical shell thin walled, with large, irregular, roundish pores and crested three-sided bars; inner cortical shell with regular, circular, hexagonally formed pores (four times as broad as the bars). Both medullary shells with simple, small, regular, circular pores (fig. 5a). Twelve radial spines three-sided prismatic, dagger-shaped, with three teeth, as long as the diameter of the innermost shell.

Dimensions.—Diameter of the four shells—(A) 0.24, (B) 0.12, (C) 0.08, (D) 0.04; meshes of the outer shell 0.02 to 0.04; length of the spines 0.04.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 105. Cromyechinus,^[118] Haeckel, 1881, Prodromus, p. 454.

Definition.—Astrosphærida with four concentric lattice-spheres and numerous simple spines of two different kinds; larger main spines and smaller by-spines.

The genus Cromyechinus differs from Cromyomma in the same way as Echinomma from Actinomma; the radial spines being differentiated into two different kinds; a larger number of small by-spines, and a smaller number of large main spines.

1. Cromyechinus icosacanthus, n. sp. (Pl. 30, fig. 1).

Radial proportion of the three spheres = 1 : 2 : 6 : 8. Outer cortical shell very delicate, with very small, regular, circular pores, covered with very numerous bristle-shaped by-spines, half as long as the radius; inner cortical shell with very large, irregular, polygonal pores, three to eight times as broad as the bars. Both medullary shells with regular, circular pores, connected with the former by twenty regularly disposed, very thin bars; these are prolonged outside into twenty very stout, three-sided prismatic main spines, as long as the radius, which arise from the inner cortical shell, and at the distal end are cuspidate.

Dimensions.—Diameter of the four shells—(A) 0.16, (B) 0.13, (C) 0.04, (D) 0.02; pores of the outer cortical shell 0.003, of the inner 0.03, bars 0.003; length of the spines 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Cromyechinus dodecacanthus, n. sp. (Pl. 30, figs. 3, 3a).

Radial proportion of the four spheres = 1 : 3 : 10 : 12. Outer cortical shell very delicate, with very small, regular, circular pores, covered with numerous short bristle-shaped by-spines, scarcely one-fourth as long as the radius; inner cortical shell with very large, irregular, polygonal pores, twice to six times as broad as the bars. Both medullary shells with very small, regular, circular pores, connected with the former by twelve regularly disposed, thin radial beams; these are prolonged outside into twelve strong, three-sided pyramidal main spines, one-third as long as the shell diameter. (Differs from the foregoing only in the number and form of the radial spines.)

Dimensions.—Diameter of the four shells—(A) 0.12, (B) 0.1, (C) 0.03, (D) 0.01; pores of the outer cortical shell 0.002, of the inner 0.02, bars 0.002; length of the spines 0.04, basal breadth 0.01.

Habitat.—South Atlantic, Station 325, surface.

3. Cromyechinus polyacanthus, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Outer cortical shell of the same structure as the inner, with irregular, roundish pores, twice to six times as broad as the bars. Both medullary shells with small, regular, circular pores, twice as broad as the bars. Connecting radial beams forty to sixty, thin, cylindrical, prolonged outside into forty to sixty strong conical main spines, about as long as the radius. Between these, numerous thin bristle-shaped by-spines, nearly of the same length.

Dimensions.—Diameter of the four shells—(A) 0.25, (B) 0.2, (C) 0.05, (D) 0.025; pores of both cortical shells 0.01 to 0.03; length of the spines 0.12.

Habitat.—North Pacific, Station 237, surface.

Genus 106. Cromyodrymus,^[119] Haeckel, 1881, Prodromus, p. 454.

Definition.—Astrosphærida with four concentric lattice-spheres and numerous branched radial spines.

The genus Cromyodrymus differs from its ancestral form, Cromyomma, in the ramification of the radial spines, and exhibits therefore the same relation to it that Pityomma among the Actinommida bears to Actinomma.

1. Cromyodrymus quadricuspis, n. sp. (Pl. 30, figs. 7, 7a).

Radial proportion of the four shells = 1 : 3 : 6 : 12. All four shells with regular, circular pores, about twice as broad as the bars. Radial proportion of the pores in the four shells = 2 : 4 : 2 : 1. Radial spines fifty to sixty, three-sided prismatic, half as long as the radius, with three recurved teeth, each spine in this way bearing four points.

Dimensions.—Diameter of the four shells—(A) 0.16, (B) 0.08, (C) 0.04, (D) 0.013; length of the spines 0.03 to 0.04, breadth 0.007.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Cromyodrymus abietinus, n. sp. (Pl. 30, fig. 6).

Radial proportion of the four shells = 1 : 2 : 5 : 11. All four shells with irregular, roundish pores, twice to four times as broad as the bars. Radial proportion of the pores in the four shells = 9 : 3 : 2 : 1. Radial spines eighty to one hundred and twenty, about as long as the radius, branched like a pine tree, with six to twelve ramified branches.

Dimensions.—Diameter of the four shells—(A) 0.22, (B) 0.1, (C) 0.04, (D) 0.02; length of the spines 0.12, breadth 0.006.

Habitat.—South-east Pacific (Juan Fernandez), Station 299, surface.

Subfamily Caryommida,^[120] Haeckel.

Arachnosphærida, Haeckel, 1862, Monogr. d. Radiol., p. 354; Prodromus, 1881, p. 454.

Definition.—Astrosphærida with five or more concentric spherical lattice-shells.

Genus 107. Caryomma,^[121] n. gen.

Definition.—Arachnosphærida with five to six or more concentric spherical lattice-shells; two inner (intracapsular) medullary and three or more outer (extracapsular) cortical shells, composed of ordinary lattice-work; distance between the former and the latter greater than between any other two shells.

The genus Caryomma may be regarded as a Cromyomma, in which the number of the cortical shells is increased to three, four, or more. These lie outside the central capsule, whilst two medullary shells lie within it, and are connected with the former by numerous radial spines piercing the wall of the capsule. The ordinary lattice-work is not arachnoidal, as in the three following genera.

1. Caryomma regulare, n. sp.

Radial proportion of the five shells = 1 : 2 : 6 : 8 : 10. All five shells with regular, circular pores, twice to three times as broad as the bars, and gradually increasing in size from the innermost to the outermost shell. Radial beams connecting them twenty, prolonged on the surface into twenty stout, three-sided pyramidal, radial spines, half as long as the radius, regularly disposed.

Dimensions.—Diameter of the five shells—(A) 0.25, (B) 0.2, (C) 0.15, (D) 0.05, (E) 0.025.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Caryomma irregulare, n. sp.

Radial proportion of the six shells = 1 : 2.5 : 8 : 10.5 : 13 : 15. Both inner (medullary) shells with regular, circular pores, the other four (cortical) shells with irregular, roundish pores, gradually increasing in size from the innermost to the outermost shell. Radial spines sixty to eighty, pyramidal, irregularly disposed.

Dimensions.—Diameter of the six shells—(A) 0.3, (B) 0.26, (C) 0.21, (D) 0.16, (E) 0.05, (F) 0.02.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 108. Arachnopila,^[122] n. gen.

Definition.—Astrosphærida with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin cobweb-like network; innermost shell with hexagonal (regular) or polygonal (irregular) meshes; other shells with simple triangular meshes, without diagonal threads between them.

The genus Arachnopila, together with the two following genera, forms the peculiar small group of large Arachnosphærida, separated from the true Caryommida by the totally different structure and disposition of the numerous concentric shells; the former exhibits a similar relation to the latter that the Diplosphærida bears to the Elatommida among the dispherical Haliommida. The concentric shells (five to ten or more) lie outside the central capsule, and are composed of very delicate, cobweb-like threads. From the innermost shell arise numerous, three-sided prismatic, very long spines, from which at equal regular distances arise lateral branches (three pairs from each spine, and one pair from each corner). In Arachnopila these threads pass directly from one spine to the other, and form simple, large, triangular meshes between them. The concentric shells are not connected by interwoven diagonal threads.

1. Arachnopila hexagonella, n. sp.

Innermost shell with regular hexagonal pores; its diameter twice as long as the equal distance between every two concentric shells. Radial spines twenty to forty, each with twenty to twenty-four verticils.

Dimensions.—Diameter of the innermost shell 0.1; distance between the concentric shells 0.05.

Habitat.—Central Pacific, Station 271, surface.

2. Arachnopila polygonella, n. sp.

Innermost shell with irregular, polygonal pores; its diameter fully as long as the equal distance between every two concentric shells. Radial spines sixty to eighty, each with twelve to sixteen verticils.

Dimensions.—Diameter of the innermost shell 0.04; distance between the concentric shells 0.04.

Habitat.—Central Pacific, Station 266, surface.

Genus 109. Arachnopegma,^[123] Haeckel, 1881, Prodromus, p. 454.

Definition.—Astrosphærida with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin, cobweb-like network; innermost shell with hexagonal or polygonal meshes; other shells with simple triangular meshes, connected to one another by diagonal threads between them.

The genus Arachnopegma differs from its ancestral form Arachnopila, in the possession of peculiar diagonal threads, which connect the verticils or nodal-points of every two neighbouring radial spines in two different neighbouring concentric shells. In this case, therefore, not only do triangular meshes lie in the spherical faces of the concentric spheres, but also between them, in numerous oblique diagonal planes; a very rare and remarkable structure, and forming a transition to spongy shells.

1. Arachnopegma verticillatum, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter is the same as the equal distance between each of the two shells. Threads of the network smooth. Radial spines twenty to forty, each with fifteen to twenty verticils.

Dimensions.—Diameter of the innermost shell 0.04, distance between the concentric shells 0.03 to 0.04.

Habitat.—Central Pacific, Station 266, surface.

2. Arachnopegma longispinum, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter half as large as the equal distance between every two shells. Threads of the network dentated or with small knots. Radial spines fifty to sixty, each with twenty to twenty-five verticils.

Dimensions.—Diameter of the innermost shell 0.02; distance between the concentric shells 0.04 to 0.05.

Habitat.—Central Pacific, Station 272, surface.

3. Arachnopegma increscens, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter quite as large as the distance between it and the second shell; only half as large as the distance between the fourth and fifth shells. Forty to fifty radial spines, each with fifteen to twenty verticils.

Dimensions.—Diameter of the innermost shell (A) 0.025; distance between the following shells—A, B = 0.025, B, C = 0.03, C, D = 0.04, D, E = 0.048, E, F = 0.056, F, G = 0.064, &c.

Habitat.—Central Pacific, Station 274, surface.

Genus 110. Arachnosphæra,^[124] Haeckel, 1862, Monogr. d. Radiol., p. 355.

Definition.—Astrosphærida with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin cobweb-like network; innermost shell with hexagonal (regular) or polygonal (irregular) meshes; other shells with larger, irregular, polygonal meshes.

The genus Arachnosphæra (accurately described by me in 1862, loc. cit.) differs from the two preceding genera in the irregular form of the large meshes in all shells (except often the innermost). This is caused by the ramification of the thin threads, which on each shell connect the neighbouring spines. In Arachnopila and Arachnopegma the threads pass directly and undivided from each spine to the neighbouring spine (three pairs from the three edges), and therefore all meshes are triangular. In Arachnosphæra they become polygonal by irregular ramification of the threads. There are here no diagonal threads.

Subgenus 1. Arachnosphærella, Haeckel.

Definition.—Pores of the innermost shell regular, hexagonal.

1. Arachnosphæra oligacantha, Haeckel.

Arachnosphæra oligacantha, Haeckel, 1862, Monogr. d. Radiol., p. 356, Taf. x. fig. 2, Taf. xi. fig. 3.

Innermost shell with regular, hexagonal meshes; its diameter three times as long as the equal distances between every two concentric shells. Fifteen to twenty radial spines scattered at wide intervals, each with six to eight verticils.

Dimensions.—Diameter of the innermost shell 0.12; distance between the concentric shells 0.04 to 0.05.

Habitat.—Mediterranean (Messina), surface, Haeckel.

2. Arachnosphæra myriacantha, Haeckel.

Arachnosphæra myriacantha, Haeckel, 1862, Monogr. d. Radiol., p. 357, Taf. x. fig. 3, Taf. xi. fig. 4.

Innermost shell with regular, hexagonal meshes; its diameter twice as long as the equal distances between every two concentric shells. At each nodal-point occurs one radial spine with six to eight verticils (spines in all one hundred to one hundred and twenty or more).

Dimensions.—Diameter of the innermost shell 0.1; distance between the concentric shells 0.04 to 0.05.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

3. Arachnosphæra dolichacantha, n. sp.

Innermost shell with regular, hexagonal meshes, very small; its diameter only as long as the equal distances between every two concentric shells. At each nodal-point occurs one radial spine with twelve to sixteen verticils (altogether thirty to forty spines).

Dimensions.—Diameter of the innermost shell 0.05; distance between the concentric shells 0.04 to 0.05.

Habitat.—Central Pacific, Station 265 to 274, surface.

4. Arachnosphæra increscens, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter three times as long as the distance between it and the second shell, quite as long as the distance between the fifth and sixth shells; the distances between the concentric shells gradually increasing from the centre. Radial spines about fifty to sixty, each with six to eight verticils.

Dimensions.—Diameter of the innermost shell (A) 0.75; distances between the following shells—A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E, F = 0.075, &c.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 2. Arachnosphæromma, Haeckel.

Definition.—Pores of the innermost shell irregular, polygonal.

5. Arachnosphæra tenuissima, n. sp.

Innermost shell with irregular, polygonal meshes; its diameter twice as long as the equal distance between every two concentric shells. Forty to fifty radial spines, each with twelve to sixteen verticils.

Dimensions.—Diameter of the innermost shell 0.1, distance between the concentric shells 0.04 to 0.05.

Habitat.—South Atlantic, Station 332, surface.

6. Arachnosphæra velaris, n. sp.

Innermost shell with irregular, polygonal meshes; its diameter twice as long as the distance between it and the second shell, quite as long as the distance between the third and fourth shells; the distance between the concentric shells gradually increasing from the centre. Radial spines twenty to thirty, each with ten to twelve verticils.

Dimensions.—Diameter of the innermost shell (A) 0.5; distances of the following shells—A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E, F = 0.075.

Habitat.—Tropical Atlantic, Station 347, surface.

Subfamily Spongiommida,^[125] Haeckel.

Definition.—Astrosphærida with spongy spherical or polyhedral shell (with or without enclosed concentric lattice-shells).

Genus 111. Spongiomma,^[126] n. gen.

Definition.—Astrosphærida with solid spongy sphere, with numerous simple radial spines, but without latticed medullary shells.

The genus Spongiomma differs from its ancestral form, Styptosphæra, in the development of simple radial spines on the surface of the solid sphere, the entire mass of which is composed of an irregular, spongy wicker-work.

Subgenus 1. Spongiommella, Haeckel.

Definition.—Radial spines on the surface of the spongy sphere all of the same shape.

1. Spongiomma radiatum, n. sp.

Spongy framework of the solid sphere of the same structure throughout, with small, irregular, polyhedral meshes and very thin thread-like bars. From the surface arise very numerous (one hundred and twenty to one hundred and sixty or more) straight, bristle-shaped radial spines, as long as the radius of the sphere (counting from the middle part of it).

Dimensions.—Diameter of the spongy sphere 0.2; length of the radial spines 0.1.

Habitat.—Central Pacific, Station 272, surface.

2. Spongiomma denticulatum, n. sp.

Spongy framework of the solid sphere of the same structure throughout, with small, almost equal meshes, four to eight times as broad as the thin, elegantly denticulated bars; from the surface arise very numerous (two hundred to three hundred or more) curved, radial spines, as long as the radius, and of the same form as the bars.

Dimensions.—Diameter of the sphere 0.25; length of the spines 0.12.

Habitat.—Central Pacific, Station 274, surface.

3. Spongiomma spathillatum, n. sp.

Spongy framework in the central part of the sphere much denser and darker, and with smaller meshes than in the peripheral part in which are very thin bars. Entire surface covered with innumerable short, bristle-shaped radial spines, only one-eighth as long as the radius, of the same elegant form as in Octodendron spathillatum (Pl. 18, figs. 2, 4); each spine developed in a zig-zag fashion, with very small beards, with a delicate spathillum (or coronal of beard spines) at the distal end.

Dimensions.—Diameter of the spheres 0.16; length of the spines 0.01.

Habitat.—South Pacific, Station 295, surface.

4. Spongiomma clavatum, n. sp.

Spongy framework in the central part of the sphere much denser and darker than in the peripheral part. On the surface are sixty to eighty stout, club-shaped radial spines, as long as the radius of the sphere, in the proximal half three-sided prismatic, with three dentated edges; they begin at the middle of the radius (where the denser inner framework changes into the looser outer) and are very thin at first but increase slowly in thickness towards the truncated distal end. (Similar to Centrocubus rhopalophorus, Pl. 18, fig. 1, but without the cubical medullary shell.)

Dimensions.—Diameter of the sphere 0.4; length of the spines 0.2.

Habitat.—North Pacific, Station 241, surface.

Subgenus 2. Spongiommura, Haeckel.

Definition.—Radial spines on the surface of the spongy sphere of two different kinds; large main spines and small by-spines.

5. Spongiomma helioides, n. sp.

Spongy framework of the sphere everywhere of the same structure, with almost equal meshes, ten to twelve times as broad as the bars. Sixteen to twenty radial main spines, longer than the shell diameter, three-sided prismatic, with three serrated edges, beginning about the middle of the radius and increasing in thickness to the truncated distal end. Between them occur numerous thin, bent, bristle-shaped by-spines. (Very similar to Spongosphæra helioides, Monogr. d. Radiol., Taf. xii. figs. 11-13, but without medullary shells.)

Dimensions.—Diameter of the sphere 0.3; length of the main spines 0.4, of the by-spines 0.01.

Habitat.—Tropical Atlantic, Station 352, surface.

6. Spongiomma multiaculeum, Haeckel.

Spongechinus multiaculeatus, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 29, Taf. v. figs. 60-63.

Spongy framework of the sphere very compact, with small meshes, scarcely broader than the bars; four to eight large main spines, three-sided pyramidal, longer than the shell radius; numerous (thirty to forty) thin by-spines, scarcely half as long.

Dimensions.—Diameter of the sphere 0.16; length of the main spines 0.11, of the by-spines 0.03.

Habitat.—Fossil in the Alpine Jura, Schafberg near Salzburg (Dunikowski).

7. Spongiomma asteroides, n. sp.

Spongy framework in the central part of the sphere much denser and darker than in the peripheral part. Sixty to eighty cylindro-conical main spines, as long as the radius, between them are numerous straight, bristle-shaped by-spines half that length.

Dimensions.—Diameter of the sphere 0.28; length of the main spines 0.16, of the by-spines 0.08.

Habitat.—South Atlantic, Station 325, surface.

Genus 112. Spongodrymus,^[127] Haeckel, 1881, Prodromus, p. 456.

Definition.—Astrosphærida with solid spongy sphere, without latticed medullary shell, with numerous branched radial spines.

The genus Spongodrymus differs from the preceding Spongiomma in the ramification of the numerous radial spines, covering the surface of the solid spongy sphere.

1. Spongodrymus elaphococcus, n. sp. (Pl. 18, fig. 9).

Spongy framework of the solid sphere equal throughout, on the surface arising in the form of very numerous (sixty to eighty or more) spongy cones with rather rhomboidal meshes. Each cone is prolonged into a very thin, irregularly curved radial spine, which is twice as long as the shell diameter, simple in the proximal half, branched like a tree in the distal half; each arborescent spine has from sixteen to thirty-two terminal branches, which fall in one spherical face. The branches of neighbouring spines are partly connected by anastomoses, so that they begin to form an outer spherical shell (cortical shell) with a looser spongy framework.

Dimensions.—Diameter of the whole spherical skeleton (sphere formed by the distal ends of the dichotomous branches) 0.9, of the inner solid spongy sphere 0.02.

Habitat.—Tropical Atlantic, Station 349, surface.

2. Spongodrymus abietinus, n. sp.

Spongy framework denser and darker in the central part of the sphere than in the peripheral part, with rather coarse meshes and thick bars. From the surface arise very numerous (sixty to eighty) stout, radial branches, as long as the shell radius, branched like a pine tree (with six to twelve ramified branches). Similar in structure to Cromyodrymus abietinus (Pl. 30, fig. 6), but with a quite irregular spongy texture in the central sphere.

Dimensions.—Diameter of the sphere 0.3; length of the spines 0.015.

Habitat.—Central Pacific, Station 272, surface.

Genus 113. Spongechinus,^[128] Haeckel, 1881, Prodromus, p. 456.

Definition.—Astrosphærida with hollow, spongy sphere, without latticed medullary shell in the central cavity, and with numerous simple radial spines.

The genus Spongechinus differs from its ancestral form, Plegmosphæra, in the development of numerous radial spines on the surface of the spongy sphere, within which is enclosed a large spherical central cavity.

1. Spongechinus setosus, n. sp.

Spongy sphere three times as broad as its inner cavity, with a very delicate, equal framework. Entire surface covered with short, straight, bristle-shaped radial spines, about half as long as the radius.

Dimensions.—Diameter of the sphere 0.2, of its inner cavity 0.07; length of the spines 0.05.

Habitat.—North Atlantic, Azores, surface.

2. Spongechinus serrulatus, n. sp.

Spongy sphere twice as broad as its inner cavity, with a delicate, equal framework. Entire surface covered with short, curved, radial spines, which are elegantly denticulated, and as long as the shell radius.

Dimensions.—Diameter of the sphere 0.3, of its cavity 0.15; length of the spines 0.15.

Habitat.—Central Pacific, Station 274, surface.

3. Spongechinus cavus, n. sp.

Spongy sphere only one-fourth broader than the large inner cavity, its spongy wall being only one-fourth as thick as the radius, composed of three to four strata of irregular, small meshes. Surface covered with short, bristle-shaped, curved spines, one-third as long as the radius.

Dimensions.—Diameter of the sphere 0.5, of its inner cavity 0.4; length of the spines 0.08.

Habitat.—North Atlantic, Station 354, surface.

Genus 114. Spongothamnus,^[129] n. gen.

Definition.—Astrosphærida with hollow, spongy sphere, without latticed medullary shell in the central cavity, and with numerous branched radial spines.

The genus Spongothamnus differs from the preceding Spongechinus in the ramification of the numerous radial spines, covering the surface of the hollow spongy sphere; it therefore exhibits the same relation to the latter that Spongodrymus bears to Spongiomma.

1. Spongothamnus furcatus, n. sp.

Spongy sphere twice as broad as its inner cavity, with very delicate bars, and irregular, dense framework. From the surface arise one hundred and fifty to one hundred and eighty thin, forked, bristle-shaped spines, half as long as the radius; both fork branches one-third as long as the basal or simple part.

Dimensions.—Diameter of the sphere 0.3, of its inner cavity 0.15; length of the spines 0.08.

Habitat.—North Pacific, Station 241, surface.

2. Spongothamnus scoparius, n. sp.

Spongy sphere four times as broad as its inner cavity, with thick bars and rather loose framework. From the surface arise sixty to eighty broom-shaped radial spines, as long as the radius, each in the basal half simple, in the distal half with six to twelve irregularly ramified branches (similar to the spines of Cromyodrymus abietinus, Pl. 30, fig. 6).

Dimensions.—Diameter of the sphere 0.4, of the inner cavity 0.1; length of the spines 0.2.

Habitat.—Central Pacific, Station 271, surface.

Genus 115. Spongopila,^[130] Haeckel, 1881, Prodromus, p. 456.

Definition.—Astrosphærida with a single, spherical, latticed medullary shell, immediately enveloped by the spongy framework of the cortical shell; on the surface of the latter are numerous radial spines.

The genus Spongopila is a Spongoplegma with radial spines. On the other hand it may be derived either from Elaphococcus, by communication of the branched spines, or from Arachnosphæra, by development of spongy branches between the concentric spheres.

1. Spongopila dichotoma, n. sp.

Medullary shell with regular, hexagonal meshes, six times as broad as the bars. From each nodal-point (between every three meshes) arises a bristle-shaped radial spine, which is dichotomously branched. By communication of the neighbouring branches the loose spongy framework of the spherical cortical shell is formed, which is four times as broad as the medullary shell. On the surface occur very numerous bristle-shaped radial spines, as long as the diameter of the medullary shell. (May be derived from Elaphococcus.)

Dimensions.—Diameter of the spongy cortical shell 0.3, of the medullary shell 0.08.

Habitat.—Tropical Atlantic, Station 347, surface.

2. Spongopila verticillata, n. sp.

Medullary shell with regular, hexagonal meshes, four times as broad as the bars. From its surface arise forty to sixty, three-sided prismatic radial spines, bearing eight to ten verticils of lateral branches, each verticil with six forked branches (two from each edge). By irregular ramification of these branches, and communication in all directions, the loose spongy framework of the cortical shell originates, which is six times as broad as the medullary shell. The free distal ends of the spines are as long as the shell radius. (May be derived from Arachnosphæra.)

Dimensions.—Diameter of the spongy cortical shell 0.6, of the medullary shell 0.1.

Habitat.—Tropical Pacific, Station 200, surface.

Genus 116. Rhizoplegma,^[131] Haeckel, 1881, Prodromus, p. 456.

Definition.—Astrosphærida with a single, spherical, latticed medullary shell, which is not armed with by-spines, but connected by stout radial main spines with the spongy cortical shell.

The genus Rhizoplegma is immediately allied to the foregoing Spongopila, but differs from it in the large interval separating both shells. In this interval lies the wall of the central capsule, which is only pierced by the radial spines connecting both shells.

Subgenus 1. Rhizoplegmarium, Haeckel.

Definition.—No free lateral branches of the radial spines between the two shells.

1. Rhizoplegma polyacanthum, n. sp.

Spongy cortical shell with a very fine dense framework and nearly smooth surface (without superficial by-spines). Its inner cavity is four times as broad as the medullary shell, which exhibits regular, hexagonal meshes. Radial spines sixty to eighty, three-sided prismatic, with three smooth edges, without lateral branches between both shells; their free outer part as long as the shell radius.

Dimensions.—Diameter of the spongy cortical shell 0.3, of its inner cavity 0.2, of the medullary shell 0.05.

Habitat.—Central Pacific, Station 274, surface.

2. Rhizoplegma spirale, n. sp.

Spongy cortical shell with a very delicate loose framework and bristly surface. Its inner cavity three times as broad as the medullary shell, which exhibits regular, hexagonal meshes. Radial spines thirty to forty, prismatic, with three smooth, spirally contorted edges, without lateral branches between the two shells; their free outer part half as long as the shell radius.

Dimensions.—Diameter of the spongy cortical shell 0.2, of its inner cavity 0.12, of the medullary shell 0.04.

Habitat.—Central Pacific, Station 265, surface.

3. Rhizoplegma trigonacantha, n. sp.

Spongy cortical shell with a rather loose framework and coarse bars, with nearly smooth surface (without by-spines). Its inner cavity twice as broad as the medullary shell, which exhibits irregular, roundish pores. Radial spines forty to sixty, prismatic, with three smooth straight edges, without free branches between the two shells; their outer pyramidal part only one-third of the shell radius. (Very similar to the common Rhizosphæra trigonacantha, but with simple medullary shell.)

Dimensions.—Diameter of the spongy shell 0.2, of its inner cavity 0.16, of the medullary shell 0.08.

Habitat.—North Atlantic, Station 353, surface.

Subgenus 2. Rhizoplegmidium, Haeckel.

Definition.—Between the two shells free lateral branches arise from the three edges of the radial spines.

4. Rhizoplegma radicatum, n. sp. (Pl. 15, figs. 9, 9a).

Spongy cortical shell with a very loose framework; on the surface are innumerable thin, forked, or repeatedly dichotomous by-spines. Its inner cavity three times as broad as the medullary shell, which exhibits regular, hexagonal meshes (fig. 9a). Radial spines twelve, prismatic, with straight dentated edges, their outer pointed part as long as the shell radius. Each spine between the two shells has a verticil of three forked lateral branches (fig. 9a). The central capsule completely distends the medullary shell, and forces out through each mesh a hernia-shaped process (fig. 9).

Dimensions.—Diameter of the spongy shell 0.5, of its inner cavity 0.25, of the medullary shell 0.08.

Habitat.—Central Pacific, Station 271, surface.

5. Rhizoplegma lychnosphæra, n. sp. (Pl. 11, fig. 5).

Lychnosphæra rhizoplegma, Haeckel, 1879, Atlas (pl. xi. fig. 5).

Spongy cortical shell with a very loose framework, composed of long thin beams as in Lychnosphæra regina (Pl. 11, figs. 1-4). Surface covered with short bristles. Its inner cavity six times as broad as the medullary shell, which exhibits regular, hexagonal meshes. Radial spines twelve, prismatic, with three smooth edges; their outer pointed part half as long as the shell radius. Each spine has three verticils of three forked branches; the first verticil is free between the two shells, while the two following verticils, by communication of their ramules, form the irregular framework. Central capsule with many herniæ, forced out through the meshes of the medullary shell (fig. 5).

Dimensions.—Diameter of the spongy shell 0.7, of its inner cavity 0.45, of the medullary shell 0.07.

Habitat.—South Pacific, Station 284, surface.

Genus 117. Lychnosphæra,^[132] Haeckel, 1881, Prodromus, p. 453.

Definition.—Astrosphærida with a single, spherical, latticed medullary shell, which is armed with free radial by-spines, and connected by stout radial main spines with the spongy cortical shell.

The genus Lychnosphæra, known only by one single, large, and very remarkable species, mainly differs from the foregoing in the development of free radial by-spines on the surface of the medullary shell, and in the free interval between it and the cortical shell; but beyond this the loose spongy framework of the latter exhibits a very remarkable structure, figured in Pl. 11.

1. Lychnosphæra regina (Pl. 11, figs. 1-4).

Medullary shell (fig. 3) with regular, circular, hexagonally framed pores, twice as broad as the bars; from each hexagon-corner arises a radial, bristle-shaped by-spine, as long as the diameter. Twelve radial main spines each as broad as one of the meshes, three-sided prismatic, six to eight times as long as the medullary shell. From their three leaf-shaped (often somewhat denticulated or spirally contorted) edges arise four verticils of lateral branches, each composed of three forked, thin branches. The forked branches of the first verticil end free between the two shells (figs. 2, 3), while the two following verticils are ramified, and, by anastomosis of their branches, compose the loose spongy framework of the cortical shell. On the surface of the latter arise numerous radial (zig-zag-shaped) by-spines. The fourth verticil is terminal, with three shorter, thicker, dentated, simple branches, which constitute, together with the distal apex of the spine itself, a bunch of four terminal spines. The large central capsule completely distends the medullary shell, and forces out by its pores numerous club-shaped herniæ (fig. 1).

Dimensions.—Diameter of the spongy cortical shell 0.6, of its inner cavity 0.4, of the central capsule 0.22, of the medullary shell 0.06; length of the radial spines 0.4, breadth 0.01.

Habitat.—Central Pacific, Station 271, surface.

Genus 118. Centrocubus,^[133] n. gen.

Definition.—Astrosphærida with a single, cubical medullary shell, immediately surrounded by the spongy framework of the cortical shell; from the eight corners of the central cube arise eight primary radial spines, and often others from the framework between them.

The genus Centrocubus and the following closely allied Octodendron may represent a peculiar small group of Spongiommida, remarkable for the regular, cubical form of the medullary shell, which is composed of twelve thin rods, corresponding to the twelve edges of a mathematical cube; from the eight corners invariably arise eight primary radial spines, the branches of which form the spongy cortical shell.

1. Centrocubus octostylus, n. sp.

Radial spines eight, arising from the eight corners of the cubiform, regular, medullary shell, gradually increasing in thickness towards the club-shaped distal end, which is five to six times as broad as the central end. From the three denticulate edges of each spine arise six to eight lateral branches, which ramify irregularly and form by their anastomosis the spongy framework which is of nearly similar structure throughout, and with large loose meshes. The free distal part of each spine is half as long as the enclosed part.

Dimensions.—Diameter of the sphere 0.6, of the central cube 0.02; length of the spines 0.15, distal thickness 0.02.

Habitat.—Central Pacific, Station 271, surface.

2. Centrocubus cladostylus, n. sp. (Pl. 18, fig. 1).

Radial spines thirty-two, club-shaped, at the distal end eight to ten times as broad as at the basal end. Eight primary spines arise from the eight corners of the regular, cubiform medullary shell, and from these, in the form of lateral branches, twenty-four secondary spines arise with concavely curved bases (three from the three denticulate edges of each spine, at nearly equal distances from the centre). The free distal end of each of the thirty-two spines is of the same shape, about half as long as the radius of the spongy sphere; framework much looser in the outer than in the inner part.

Dimensions.—Diameter of the sphere 0.8, of the central cube 0.02; length of the spines 0.2, distal thickness 0.02.

Habitat.—North Pacific, Station 256, surface.

3. Centrocubus polystylus, n. sp.

Radial spines sixty to eighty, club-shaped, four to six times as broad at the distal as at the basal end. Eight primary spines arise from the eight corners of the regular, cubiform medullary shell, the remainder either springing as lateral branches from the three denticulate corners of the former, or arising within the spongy framework, which is much denser and darker in the central than in the peripheral part. The free distal end of each spine is one-third as long as the radius.

Dimensions.—Diameter of the sphere 0.9, of the central cube 0.02; length of the spines 0.15, distal thickness 0.02.

Habitat.—South Pacific, Station 295, surface.

Genus 119. Octodendron,^[134] n. gen.

Definition.—Astrosphærida with a single, cubical medullary shell, and eight primary radial spines arising from its eight corners; these are connected at equal distances by a latticed, spherical, cortical shell, from which the spongy framework directly springs; often from the latter secondary radial spines arise.

The genus Octodendron has the same regular, cubical medullary shell as the preceding Centrocubus, but differs from it in the wide interval separating the medullary shell from the inner spherical face of the spongy cortical shell, the two being connected only by eight radial beams, arising from the eight corners of the cube.

Subgenus 1. Octodendridium, Haeckel.

Definition.—Only eight primary radial spines, arising from the eight corners of the central cube.

1. Octodendron cubocentron, n. sp. (Pl. 18, fig. 3).

Radial spines eight, club-shaped, with three denticulate, straight edges, twice as long as the diameter of the central cavity of the cubical spongy shell; the inner face of the latter (or the "inner cortical shell") exhibits the form of a large cube, the spongy sides of which are parallel with the simple square sides of the central cube. The thin eight radial beams, connecting the corresponding corners of both cubes, are not thicker than the edge-bars of the central cube, whilst their outer prolongations are much thicker, with four to six verticils of lateral branches. Surface of the thin walled, loose, spongy shell armed with short simple thorns.

Dimensions.—Diameter of the spongy shell 0.2, of its inner cavity 0.1, of the central cube 0.02; length of the spines 0.2 (from the centre 0.3).

Habitat.—Central Pacific, Station 266, surface.

2. Octodendron spirale, n. sp.

Radial spines eight, three-sided prismatic, three times as long as the diameter of the inner shell-cavity; their three edges denticulated and spirally contorted around the spine axis. Thickness of the loose spongy shell-wall equal to the radius of the inner cavity, three times as large as the central cube. Surface covered, with numerous thin, bristle-shaped, bent spinules.

Dimensions.—Diameter of the spongy shell 0.24, of its inner cavity 0.12, of the central cube 0.02; length of the spines 0.4, breadth 0.01.

Habitat.—North Pacific, Station 254, surface.

3. Octodendron pinetum, n. sp.

Radial spines eight, three-sided prismatic, three to four times as long as the diameter of the inner shell-cavity, with three spirally contorted edges. From each spine arise at equal distances (equal to the half radius of the cavity) fifteen to twenty verticils of branches which increase in size from the base of the spine. Each verticil is composed of six forked branches (two from each spine-edge); the inferior are richly branched, and form by their connection the loose network of the spongy cortical shell, the surface of which is covered with numerous bent threads. Each spine bears a resemblance to a pine tree.

Dimensions.—Diameter of the spongy shell 0.3, of its inner cavity 0.15, of the central cube 0.02; length of the spines 0.5 to 0.6, breadth 0.01.

Habitat.—Central Pacific, Station 272, surface.

4. Octodendron araucaria, n. sp.

Radial spines eight, three-sided prismatic, with three spirally contorted edges, eight to ten times as long as the diameter of the inner shell-cavity (the free distal portion twice to three times as long). From each spine arise at equal distances thirty to thirty-five verticils of branches, which decrease in size towards the distal end. Each verticil is composed of six forked branches (two from each spine-edge); the inferior are richly ramified and form by their connection the loose spongy framework; the distal branches bear on the free end elegant spathillæ (as in the following species). Surface covered with innumerable straight bristles, as long as the cavity radius, and ending with a spathilla. Diameter of the central capsule about equal to the radius of the spongy sphere, its membrane is double-edged.

Dimensions.—Diameter of the spongy shell 1.4 mm., of its inner cavity 0.14, of the central cube 0.02, of the central capsule 0.5 to 0.6; length of the spines 0.9 to 1.2, breadth 0.02.

Habitat.—South Pacific, Station 288, surface.

5. Octodendron spathillatum, n. sp. (Pl. 18, figs. 2, 4).

Radial spines eight, three-sided prismatic, with contorted edges, five to eight times as long as the diameter of the shell-cavity (the free part twice as long). From each spine arise ten to twelve verticils of lateral branches; each verticil composed of three forked branches. The proximal larger branches ramify richly, and form by their connection the loose spongy framework of the spherical shell; the distal smaller branches are simple or bifurcated, and the ramules are provided with an elegant spathillum at the end (fig. 4). Entire surface of the spongy sphere covered with innumerable bristle-shaped radial spines (half as long as the cavity radius), zig-zag, bent, with beards, and with a spathillum at the end.

Dimensions.—Diameter of the spongy sphere 1 mm., of its central cavity 0.15, of the central cube 0.02; length of the spines 1 to 1.2 mm., breadth 0.008.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 2. Octodendronium, Haeckel.

Definition.—Radial spines thirty-two or more, eight primary (arising from the eight corners of the central cube) and twenty-four or more secondary (between them).

6. Octodendron verticillatum, n. sp.

Radial spines thirty-two, with three denticulate straight edges, six to eight times as long as the diameter of the shell-cavity; the distal parts half free. Eight primary spines arise from the eight corners of the central cube, twenty-four secondary from the edges of these (a verticil of every three from each primary spine). Distal free parts of all thirty-two spines equal. Each spine with eight to ten verticils of forked lateral branches, without spathillæ. Surface of the spongy sphere covered with short simple bristles.

Dimensions.—Diameter of the spongy shell 0.3, of its cavity 0.12, of the central cube 0.02; length of the spines 0.7 to 1 mm., breadth 0.02.

Habitat.—South Pacific, Station 291, surface.

7. Octodendron contortum, n. sp.

Radial spines thirty-two, disposed in a similar manner to those of the former species (eight primary and twenty-four secondary); also the spongy shell of the same shape. The difference arises in the form of the spines, the three edges of which are much broader and spirally contorted around the axis; and thus the corresponding branches of the verticil do not lie in the same meridian-plane, but alternate one with another.

Dimensions.—Diameter of the spongy shell 0.4, of its cavity 0.1, of the central cube 0.02; length of the spines 0.8 to 1.2, breadth 0.04.

Habitat.—Central Pacific, Station 274, surface.

8. Octodendron arboretum, n. sp.

Radial spines sixty to ninety, three-sided prismatic, with spirally contorted and denticulate edges, six to eight times as long as the diameter of the inner shell-cavity. Eight primary arise from the eight corners of the central cube, twenty-four others from their three edges (as in the two former species); the remaining thirty to sixty spines seem to arise between the former and immediately from the dense spongy framework, which is twice as thick as the diameter of the inner shell-cavity. The numerous verticils of the free distal part are of equal shape in all the spines, composed of three forked branches in the terminal, and of more ramified branches in the inferior parts. Entire surface of the spongy shell covered with simple radial bristles, without spathillæ.

Dimensions.—Diameter of the spongy shell 0.75, of its central cavity 0.15, of the central cube 0.02; length of the spines 0.9 to 1.2, breadth 0.02.

Habitat.—Tropical Pacific, Station 225, surface.

Genus 120. Spongosphæra,^[135] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Astrosphærida with two concentric latticed medullary shells, connected by radial beams; the outer is immediately enveloped by the spongy framework, and bears numerous radial spines.

The genus Spongosphæra (in the definition here restricted) differs from Spongopila in the double medullary shell, which in the latter is simple; it exhibits to the latter the same relation that Spongodictyon among the Liosphærida bears to Spongoplegma. The outer medullary shell of Spongosphæra is immediately enveloped by the spongy wicker-work, which everywhere pierces the wall of the central capsule.

1. Spongosphæra streptacantha, Haeckel.

Spongosphæra streptacantha, Haeckel, 1862, Monogr. d. Radiol., p. 455, Taf. xxvi. figs. 1-3.

Spongy shell of polyhedric, irregular outline, the framework being prolonged sheath-like into the eight to twelve radial spines, which are quite irregularly distributed, very large, three-sided prismatic, with three serrated, spirally contorted edges; their length is twice to four times as great as the diameter of the spongy body; they arise with thinner bases from the outer medullary shell, which is three times as broad as the inner, both having roundish pores, twice to four times as broad as the bars; surface without radial by-spines.

Dimensions.—Diameter of the spongy shell 0.2 to 0.6, outer medullary shell 0.04 to 0.06, inner 0.012 to 0.016.

Habitat.—Cosmopolitan; common in all warmer seas, surface.

2. Spongosphæra polyacantha, J. Müller.

Spongosphæra polyacantha, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 32, Taf. iv. figs. 1-4.

Spongy shell spherical, with ten to twenty large radial spines, which arise with thinner bases from the medullary shell, and are prominent on the surface at different lengths; they are three-sided prismatic (not four-sided), with three leaf-shaped straight edges. Whilst the spongy framework is much looser than in the preceding species, both medullary shells have nearly the same shape.

Dimensions.—Diameter of the spongy shell 0.2 to 0.5, outer medullary shell 0.04 to 0.06, inner 0.012 to 0.016.

Habitat.—Mediterranean (Nice); Atlantic, Station 353, surface.

Subgenus Spongosphæromma, Haeckel.

Definition.—Radial spines on the surface of the spongy shell of two different kinds; large piercing main spines and small superficial by-spines.

3. Spongosphæra helioides, Haeckel.

Spongosphæra helioides, Haeckel, 1862, Monogr. d. Radiol., p.456, Taf. xii. figs. 11-13.

Spongy shell spherical, with numerous curved, bristle-shaped by-spines on the surface, as long as the radius. Main spines ten to twenty, irregularly disposed, prismatic, with three dentated, spirally contorted edges, broader toward the distal end. Outer medullary shell three times as broad as the inner, with polygonal meshes (of the same size as those in the spongy framework) and fine bars.

Dimensions.—Diameter of the spongy shell 0.2, outer medullary shell 0.02, inner 0.007.

Habitat.—Mediterranean (Messina).

4. Spongosphæra quadricuspis, n. sp.

Spongy shell spherical, with numerous curved, bristle-shaped by-spines on the surface, half as long as the radius. Main spines twenty to thirty, irregularly disposed, prismatic, with three dentated, spirally contorted edges, and at the distal end four strong pyramidal divergent teeth (three as terminations of the edges, the fourth as end of the spine axis). Outer medullary shell twice as broad as the inner, both having circular, regular pores, twice to three times as broad as the bars.

Dimensions.—Diameter of the spongy shell 0.3, outer medullary shell 0.04, inner 0.013.

Habitat.—Central Pacific, Station 272, surface.

Genus 121. Rhizosphæra,^[136] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 840.

Definition.—Astrosphærida with two concentric latticed medullary shells, connected by radial beams; from the outer arise numerous radial spines, which at equal distances are connected by a latticed spherical cortical shell, surrounded by a spongy framework.

The genus Rhizosphæra exhibits the same relation to Spongosphæra that Rhizoplegma bears to Spongopila; but in the latter the latticed medullary shell is simple, in the two former double. The wall of the central capsule is pierced only by the radial spines connecting the medullary and the cortical shells.

1. Rhizosphæra trigonacantha, Haeckel.

Rhizosphæra trigonacantha, Haeckel, 1862, Monogr. d. Radiol., p. 452, Taf. xxv. figs. 1-7.

Central cavity of the spongy cortical shell twice as broad as the diameter of the outer medullary shell. Bars of all three shells of the same breadth as the thirty to fifty (or more) radial spines, which are three-sided prismatic; their outer free distal end only as long as the diameter of the inner medullary shell.

Dimensions.—Diameter of the spongy shell 0.25, of its inner cavity 0.2, outer medullary shell 0.1, inner 0.05.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface from many Stations.

2. Rhizosphæra serrata, n. sp. (Pl. 18, figs. 5-7).

Central cavity of the spongy shell five times as broad as the diameter of the outer medullary shell. Bars of all three shells of the same breadth as the forty to sixty (or more) thin radial beams between them. These are three-sided prismatic, with denticulate edges, scarcely half as broad as their outer prolongations, which are half as long as the shell radius, and possess three spirally contorted serrated edges. (The figured specimen is a young one; in the older specimens the spongy framework of the cortical shell is much more developed.)

Dimensions.—Diameter of the spongy shell 0.3, of its central cavity 0.22, outer medullary shell 0.06, inner 0.02.

Habitat.—Central Pacific, Stations 270 to 274, surface.

3. Rhizosphæra leptomita, Haeckel.

Rhizosphæra leptomita, Haeckel, 1862, Monogr. d. Radiol., p. 453, Taf. xxv. figs. 8-10.

Central cavity of the spongy cortical shell twice as broad as the diameter of the outer medullary shell; bars of both very thin, only one-third as broad as the bars of the inner medullary shell. Radial spines thirty to fifty (or more), curved, three-sided prismatic; inside the spongy shell as thin as their bars, outside three times as broad.

Dimensions.—Diameter of the spongy shell 0.27, of its inner cavity 0.2, outer medullary shell 0.1, inner 0.05.

Habitat.—Mediterranean (Messina); Atlantic, Stations 348 to 354, surface.

↑ Ethmosphærida = Liosphærida simplicia = Monosphærida anacantha.
↑ Cenosphæra = Hollow sphere; κενός, σφαῖρα.
↑ Stigmosphæra = Sphere with central point; στίγμα, σφαῖρα.
↑ Ethmosphæra = Sieve-sphere; ἠθμός, σφαῖρα.
↑ Sethosphæra = Sieve-sphere; σῆθος, σφαῖρα.
↑ Carposphærida = Liosphærida duplicia = Dyosphærida anacantha.
↑ Carposphæra = Fruit-shaped sphere, καρπός, σφαῖρα.
↑ Liosphæra = Smooth sphere; λεῖος, σφαῖρα.
↑ Thecosphærida = Liosphærida triplicia = Triosphærida anacantha.
↑ Thecosphæra = Capsule-sphere; θήκη, σφαῖρα.
↑ Rhodosphæra = Rose-sphere; ῥόδον, σφαῖρα.
↑ Cromyosphærida = Liosphærida tetraplicia = Tetrasphærida anacantha.
↑ Cromyosphæra = Onion-sphere; χρόμυον, σφαῖρα.
↑ Caryosphærida = Liosphærida multiplicia = Polysphærida anacantha.
↑ Caryosphæra = Nut-sphere; κάρυον, σφαῖρα.
↑ Plegmosphærida = Liosphærida spongiosa = Spongosphærida anacantha.
↑ Styptosphæra = Hemp-sphere; στυπτός, σφαῖρα.
↑ Plegmosphæra = Sphere of wicker-work; πλέγμα, σφαῖρα.
↑ Spongoplegma = Spongy wickerwork; σπόγγος, πλέγμα.
↑ Spongodictyon = Spongy network; σπόγγος, δίκτυον.
↑ Loc. cit., pp. 17, 55, 1858.
↑ Abhandl. d. k. Akad. d. Wiss. Berlin, p. 55, 1858.
↑ Loc. cit., p. 530, 1862.
↑ Loc. cit., pp. 30, 133, 1879.
↑ Loc. cit., p. 471, 1881.
↑ Loc. cit., p. 535, Taf. xxxiv. fig. 1.
↑ Collosphæra = Jelly-sphere; κόλλα, σφαῖρα.
↑ Tribonosphæra = Cloak-sphere; τρίβων, σφαῖρα.
↑ Pharyngosphæra = Throat-sphere; φάρυγξ, σφαῖρα.
↑ Buccinosphæra=Trumpet-sphere; βυκάνη, σφαῖρα.
↑ Acrosphæra=Pointed-sphere; ἄκρος, σφαῖρα.
↑ Odontosphæra = Teeth-sphere; ὀδούς, σφαῖρα.
↑ Chœnicosphæra = Shell with coronel trepans; χοινίκη, σφαῖρα.
↑ Siphonosphæra = Sphere with tubes; σίφων, σφαῖρα.
↑ Mazosphæra = Teat-sphere; μαζός, σφαῖρα.
↑ Trypanosphæra = Auger-sphere; τρύπανον, σφαῖρα.
↑ Caminosphæra = Chimney-sphere; κάμινος, σφαῖρα.
↑ Solenosphæra = Sphere with tubules; σωλήν, σφαῖρα.
↑ Otosphæra = Shell with ears; ὀτοσφαῖρα.
↑ Coronosphæra = Coronal-sphere; κορόνη, σφαῖρα.
↑ Clathrosphæra = Lattice-sphere.
↑ Xanthiosphæra = Burdock-sphere; ξάνθιον, σφαῖρα.
↑ Stylosphærida = Sphæroidea dissacantha, Prodromus, p. 449.
↑ Xiphosphæra = Sword-sphere; ξίφος, σφαῖρα.
↑ Xiphostylus = Sword style; ξίφος, στῦλος.
↑ Saturnalis = Similar to Saturnus, with a ring.
↑ Stylosphæra = Sphere with styles; στῦλος, σφαῖρα.
↑ Sphærostylus = Sphere with styles; σφαῖρα, στῦλος.
↑ Saturnulus = Small Saturnus, with a ring.
↑ Amphisphæra = Sphere with spines on both poles; ἀμφί, σφαῖρα.
↑ Amphistylus = Shell with styles on both poles; ἀμφί, στῦλος.
↑ Saturninus = Similar to Saturnus, with a ring.
↑ Stylocromyum = Onion with styles; στῦλος, κρόμυον.
↑ Cromyostylus = Onion with styles; κρόμυον, στῦλος.
↑ Spongolonchis = Spongy shell with spears; σπόγγος, λογχίς.
↑ Spongostylus = Spongy shell with styles; σπόγγος, στῦλος.
↑ Spongostylidium, diminutive of Spongostylus.
↑ Staurostylida = Staurosphærida simplicia = Monosphærida tetracantha.
↑ Staurosphæra = Cross-sphere; σταυρός, σφαῖρα.
↑ Staurostylus = Cross-style; σταυρός, στῦλος.
↑ Stylostaurus, Style-cross; στῦλος, σταυρός.
↑ Staurolonchida = Staurosphærida duplicia = Dyosphærida tetracantha.
↑ Staurolonche = Crossed spear; σταυρός, λόγχη.
↑ Staurancistra = Crossed fish-hook; σταυρός, ἄγκιστρα.
↑ Staurolonchidium = Diminutive from Staurolonche.
↑ Stauroxiphos = Sword with cross; σταυρός, ξίφος.
↑ Stauracontida = Staurosphærida triplicia = Triosphærida tetracantha.
↑ Stauracontium = Crossed dart; σταυρός, ἀκόντιον.
↑ Staurocromyida = Staurosphærida quadruplicia = Tetrasphærida tetracantha.
↑ Staurocromyum = Cross-onion; σταυρός, κρόμυον.
↑ Cromyostaurus = Onion-cross; κρόμυον, σταυρός.
↑ Staurocaryida = Staurosphærida multiplicia = Polysphærida tetracantha.
↑ Staurocaryum = Cross-nut; σταυρός, κάρυον.
↑ Staurodorida = Staurosphærida spongiosa = Spongosphærida tetracantha.
↑ Staurodoras = Crossed spear; σταυρός, δόρας.
↑ Hexastylida = Cubosphærida simplicia = Monosphærida hexacantha.
↑ Hexastylus = Shell with six styles; ἕξα, στῦλος.
↑ Hexastylarium = Shell with six styles; derivation from Hexastylus.
↑ Hexastylidium = Shell with six styles; derivation from Hexastylus.
↑ Hexalonchida = Cubosphærida duplicia = Dyosphærida hexacantha.
↑ Hexalonche = Shell with six spears; ἑξαλόγχη.
↑ Hexancistra = Shell with six fish-hooks; ἑξάγκιστρα.
↑ Hexaloncharium = Shell with six spears; derivation from Hexalonche.
↑ Hexalonchidium = Shell with six spears; derivation from Hexalonche.
↑ Hexacontida = Cubosphærida triplicia = Triosphærida hexacantha.
↑ Hexacontion = Shell with six darts; ἑξακόντιον.
↑ Hexadendron = Shell with six trees; ἑξαδένδρον.
↑ Hexacontarium = Shell with six darts; derivation, from Hexacontion.
↑ Hexacromyida = Cubosphærida quadruplicia = Tetrasphærida hexacantha.
↑ Hexacromyum = Onion with six rays; ἕξα, κρόμυον.
↑ Hexacaryida = Cubosphærida multiplicia = Polysphærida hexacantha.
↑ Cubosphæra = Sphere with three axes of a cubus; κῦβος, σφαῖρα.
↑ Hexacaryum = Nut with six spines; ἕξα, κάρυον.
↑ Hexadorida = Cubosphærida spongiosa = Spongosphærida hexacantha.
↑ Cubaxonium = Shell with three axes like those of a cube; κῦβος, ἀξώνιον.
↑ Hexadoras = Shell with six spears; ἑξάδορας.
↑ Hexadoridium = Shell with six small spears; derivation from Hexadoras.
↑ Acanthosphæra = Spiny sphere; ἄκανθα, σφαῖρα.
↑ Heliosphæra = Sun sphere; ἥλιος, σφαῖρα.
↑ Conosphæra = Sphere with cones; κῶνος, σφαῖρα.
↑ Coscinomma = Sieve eye; κόσκινον, ὄμμα.
↑ Cladococcus = Nucleus with branches; κλάδος, κόκκος.
↑ Elaphococcus = Shell with harts' horn-shaped spines; ἔλαφος, κόκκος.
↑ Haliommida = Astrosphærida duplicia = Dyosphærida polycantha.
↑ Haliomma = Sea-eye; ἅλς, ὄμμα.
↑ Heliosoma = Sun-body; ἥλιος, σῶμα.
↑ Elatomma = Pine-eye; ἐλάτη, ὄμμα.
↑ Leptosphæra = Delicate sphere; λεπτός, σφαῖρα.
↑ Diplosphæra = Double sphere; διπλόος, σφαῖρα.
↑ Drymosphæra = Woody sphere; δρυμός, σφαῖρα.
↑ Astrosphæra = Star-sphere; ἄστρον, σφαῖρα.
↑ Actinommida = Astrosphærida triplicia = Triosphærida polyacantha.
↑ Actinomma = Radiant eye; ἀκτίς, ὄμμα.
↑ Echinomma = Urchin-eye; ἐχῖνος, ὄμμα.
↑ Pityomma = Pine-eye; πίτυς, ὄμμα.
↑ Cromyommida = Astrosphærida quadruplicia = Tetrasphæria polyacantha.
↑ Cromyomma = Onion-eye; κρόμυον, ὄμμα.
↑ Cromyechinus = Onion-shaped Urchin; κρόμυον, ἐχῖνος.
↑ Cromyodrymus = Onion with trees; κρόμυον, δρυμός.
↑ Caryommida = Astrosphærida multiplica = Polysphæria polyacantha.
↑ Caryomma = Nut-eye; κάρυον, ὄμμα.
↑ Arachnopila = Cobweb ball; ἀράχνη, πῖλος.
↑ Arachnopegma = Cobweb-building; ἀράχνη, πῆγμα.
↑ Arachnosphæra = Cobweb-sphere; ἀράχνη, σφαῖρα.
↑ Spongiommida = Astrosphærida spongiosa = Spongosphærida polyacantha.
↑ Spongiomma = Spongy-eye; σπόγγια, ὄμμα.
↑ Spongodrymus = Spongy wood; σπόγγος, δρῦμος.
↑ Spongechinus = Spongy Urchin; σπόγγος, ἐχῖνος.
↑ Spongothamnus = Spongy shrub; σπόγγος, θάμνος.
↑ Spongopila = Spongy ball; σπόγγος, πῖλος.
↑ Rhizoplegma = Root-shaped wicker-work; ῥῖζα, πλέγμα.
↑ Lychnosphæra = Lantern-sphere; λύχνος, σφαῖρα.
↑ Centrocubus = Shell with a central cube; κέντρον, κῦβος.
↑ Octodendron = Shell with eight trees; ὄκτω, δένδρον.
↑ Spongosphæra = Spongy sphere; σπόγγος, σφαῖρα.
↑ Rhizosphæra = Root-sphere; ῥῖζα, σφαῖρα.

[Nt25-1] Ethmosphærida = Liosphærida simplicia = Monosphærida anacantha.

[Nt26-2] Cenosphæra = Hollow sphere; κενός, σφαῖρα.

[Nt27-3] Stigmosphæra = Sphere with central point; στίγμα, σφαῖρα.

[Nt28-4] Ethmosphæra = Sieve-sphere; ἠθμός, σφαῖρα.

[Nt29-5] Sethosphæra = Sieve-sphere; σῆθος, σφαῖρα.

[Nt30-6] Carposphærida = Liosphærida duplicia = Dyosphærida anacantha.

[Nt31-7] Carposphæra = Fruit-shaped sphere, καρπός, σφαῖρα.

[Nt32-8] Liosphæra = Smooth sphere; λεῖος, σφαῖρα.

[Nt33-9] Thecosphærida = Liosphærida triplicia = Triosphærida anacantha.

[Nt34-10] Thecosphæra = Capsule-sphere; θήκη, σφαῖρα.

[Nt35-11] Rhodosphæra = Rose-sphere; ῥόδον, σφαῖρα.

[Nt36-12] Cromyosphærida = Liosphærida tetraplicia = Tetrasphærida anacantha.

[Nt37-13] Cromyosphæra = Onion-sphere; χρόμυον, σφαῖρα.

[Nt38-14] Caryosphærida = Liosphærida multiplicia = Polysphærida anacantha.

[Nt39-15] Caryosphæra = Nut-sphere; κάρυον, σφαῖρα.

[Nt40-16] Plegmosphærida = Liosphærida spongiosa = Spongosphærida anacantha.

[Nt41-17] Styptosphæra = Hemp-sphere; στυπτός, σφαῖρα.

[Nt42-18] Plegmosphæra = Sphere of wicker-work; πλέγμα, σφαῖρα.

[Nt43-19] Spongoplegma = Spongy wickerwork; σπόγγος, πλέγμα.

[Nt44-20] Spongodictyon = Spongy network; σπόγγος, δίκτυον.

[Nt45-21] Loc. cit., pp. 17, 55, 1858.

[Nt46-22] Abhandl. d. k. Akad. d. Wiss. Berlin, p. 55, 1858.

[Nt47-23] Loc. cit., p. 530, 1862.

[Nt48-24] Loc. cit., pp. 30, 133, 1879.

[Nt49-25] Loc. cit., p. 471, 1881.

[Nt50-26] Loc. cit., p. 535, Taf. xxxiv. fig. 1.

[Nt51-27] Collosphæra = Jelly-sphere; κόλλα, σφαῖρα.

[Nt52-28] Tribonosphæra = Cloak-sphere; τρίβων, σφαῖρα.

[Nt53-29] Pharyngosphæra = Throat-sphere; φάρυγξ, σφαῖρα.

[Nt54-30] Buccinosphæra=Trumpet-sphere; βυκάνη, σφαῖρα.

[Nt55-31] Acrosphæra=Pointed-sphere; ἄκρος, σφαῖρα.

[Nt56-32] Odontosphæra = Teeth-sphere; ὀδούς, σφαῖρα.

[Nt57-33] Chœnicosphæra = Shell with coronel trepans; χοινίκη, σφαῖρα.

[Nt58-34] Siphonosphæra = Sphere with tubes; σίφων, σφαῖρα.

[Nt59-35] Mazosphæra = Teat-sphere; μαζός, σφαῖρα.

[Nt60-36] Trypanosphæra = Auger-sphere; τρύπανον, σφαῖρα.

[Nt61-37] Caminosphæra = Chimney-sphere; κάμινος, σφαῖρα.

[Nt62-38] Solenosphæra = Sphere with tubules; σωλήν, σφαῖρα.

[Nt63-39] Otosphæra = Shell with ears; ὀτοσφαῖρα.

[Nt64-40] Coronosphæra = Coronal-sphere; κορόνη, σφαῖρα.

[Nt65-41] Clathrosphæra = Lattice-sphere.

[Nt66-42] Xanthiosphæra = Burdock-sphere; ξάνθιον, σφαῖρα.

[Nt67-43] Stylosphærida = Sphæroidea dissacantha, Prodromus, p. 449.

[Nt68-44] Xiphosphæra = Sword-sphere; ξίφος, σφαῖρα.

[Nt69-45] Xiphostylus = Sword style; ξίφος, στῦλος.

[Nt70-46] Saturnalis = Similar to Saturnus, with a ring.

[Nt71-47] Stylosphæra = Sphere with styles; στῦλος, σφαῖρα.

[Nt72-48] Sphærostylus = Sphere with styles; σφαῖρα, στῦλος.

[Nt73-49] Saturnulus = Small Saturnus, with a ring.

[Nt74-50] Amphisphæra = Sphere with spines on both poles; ἀμφί, σφαῖρα.

[Nt75-51] Amphistylus = Shell with styles on both poles; ἀμφί, στῦλος.

[Nt76-52] Saturninus = Similar to Saturnus, with a ring.

[Nt77-53] Stylocromyum = Onion with styles; στῦλος, κρόμυον.

[Nt78-54] Cromyostylus = Onion with styles; κρόμυον, στῦλος.

[Nt79-55] Spongolonchis = Spongy shell with spears; σπόγγος, λογχίς.

[Nt80-56] Spongostylus = Spongy shell with styles; σπόγγος, στῦλος.

[Nt81-57] Spongostylidium, diminutive of Spongostylus.

[Nt82-58] Staurostylida = Staurosphærida simplicia = Monosphærida tetracantha.

[Nt83-59] Staurosphæra = Cross-sphere; σταυρός, σφαῖρα.

[Nt84-60] Staurostylus = Cross-style; σταυρός, στῦλος.

[Nt85-61] Stylostaurus, Style-cross; στῦλος, σταυρός.

[Nt86-62] Staurolonchida = Staurosphærida duplicia = Dyosphærida tetracantha.

[Nt87-63] Staurolonche = Crossed spear; σταυρός, λόγχη.

[Nt88-64] Staurancistra = Crossed fish-hook; σταυρός, ἄγκιστρα.

[Nt89-65] Staurolonchidium = Diminutive from Staurolonche.

[Nt90-66] Stauroxiphos = Sword with cross; σταυρός, ξίφος.

[Nt91-67] Stauracontida = Staurosphærida triplicia = Triosphærida tetracantha.

[Nt92-68] Stauracontium = Crossed dart; σταυρός, ἀκόντιον.

[Nt93-69] Staurocromyida = Staurosphærida quadruplicia = Tetrasphærida tetracantha.

[Nt94-70] Staurocromyum = Cross-onion; σταυρός, κρόμυον.

[Nt95-71] Cromyostaurus = Onion-cross; κρόμυον, σταυρός.

[Nt96-72] Staurocaryida = Staurosphærida multiplicia = Polysphærida tetracantha.

[Nt97-73] Staurocaryum = Cross-nut; σταυρός, κάρυον.

[Nt98-74] Staurodorida = Staurosphærida spongiosa = Spongosphærida tetracantha.

[Nt99-75] Staurodoras = Crossed spear; σταυρός, δόρας.

[Nt100-76] Hexastylida = Cubosphærida simplicia = Monosphærida hexacantha.

[Nt101-77] Hexastylus = Shell with six styles; ἕξα, στῦλος.

[Nt102-78] Hexastylarium = Shell with six styles; derivation from Hexastylus.

[Nt103-79] Hexastylidium = Shell with six styles; derivation from Hexastylus.

[Nt104-80] Hexalonchida = Cubosphærida duplicia = Dyosphærida hexacantha.

[Nt105-81] Hexalonche = Shell with six spears; ἑξαλόγχη.

[Nt106-82] Hexancistra = Shell with six fish-hooks; ἑξάγκιστρα.

[Nt107-83] Hexaloncharium = Shell with six spears; derivation from Hexalonche.

[Nt108-84] Hexalonchidium = Shell with six spears; derivation from Hexalonche.

[Nt109-85] Hexacontida = Cubosphærida triplicia = Triosphærida hexacantha.

[Nt110-86] Hexacontion = Shell with six darts; ἑξακόντιον.

[Nt111-87] Hexadendron = Shell with six trees; ἑξαδένδρον.

[Nt112-88] Hexacontarium = Shell with six darts; derivation, from Hexacontion.

[Nt113-89] Hexacromyida = Cubosphærida quadruplicia = Tetrasphærida hexacantha.

[Nt114-90] Hexacromyum = Onion with six rays; ἕξα, κρόμυον.

[Nt115-91] Hexacaryida = Cubosphærida multiplicia = Polysphærida hexacantha.

[Nt116-92] Cubosphæra = Sphere with three axes of a cubus; κῦβος, σφαῖρα.

[Nt117-93] Hexacaryum = Nut with six spines; ἕξα, κάρυον.

[Nt118-94] Hexadorida = Cubosphærida spongiosa = Spongosphærida hexacantha.

[Nt119-95] Cubaxonium = Shell with three axes like those of a cube; κῦβος, ἀξώνιον.

[Nt120-96] Hexadoras = Shell with six spears; ἑξάδορας.

[Nt121-97] Hexadoridium = Shell with six small spears; derivation from Hexadoras.

[Nt122-98] Acanthosphæra = Spiny sphere; ἄκανθα, σφαῖρα.

[Nt123-99] Heliosphæra = Sun sphere; ἥλιος, σφαῖρα.

[Nt124-100] Conosphæra = Sphere with cones; κῶνος, σφαῖρα.

[Nt125-101] Coscinomma = Sieve eye; κόσκινον, ὄμμα.

[Nt126-102] Cladococcus = Nucleus with branches; κλάδος, κόκκος.

[Nt127-103] Elaphococcus = Shell with harts' horn-shaped spines; ἔλαφος, κόκκος.

[Nt128-104] Haliommida = Astrosphærida duplicia = Dyosphærida polycantha.

[Nt129-105] Haliomma = Sea-eye; ἅλς, ὄμμα.

[Nt130-106] Heliosoma = Sun-body; ἥλιος, σῶμα.

[Nt131-107] Elatomma = Pine-eye; ἐλάτη, ὄμμα.

[Nt132-108] Leptosphæra = Delicate sphere; λεπτός, σφαῖρα.

[Nt133-109] Diplosphæra = Double sphere; διπλόος, σφαῖρα.

[Nt134-110] Drymosphæra = Woody sphere; δρυμός, σφαῖρα.

[Nt135-111] Astrosphæra = Star-sphere; ἄστρον, σφαῖρα.

[Nt136-112] Actinommida = Astrosphærida triplicia = Triosphærida polyacantha.

[Nt137-113] Actinomma = Radiant eye; ἀκτίς, ὄμμα.

[Nt138-114] Echinomma = Urchin-eye; ἐχῖνος, ὄμμα.

[Nt139-115] Pityomma = Pine-eye; πίτυς, ὄμμα.

[Nt140-116] Cromyommida = Astrosphærida quadruplicia = Tetrasphæria polyacantha.

[Nt141-117] Cromyomma = Onion-eye; κρόμυον, ὄμμα.

[Nt142-118] Cromyechinus = Onion-shaped Urchin; κρόμυον, ἐχῖνος.

[Nt143-119] Cromyodrymus = Onion with trees; κρόμυον, δρυμός.

[Nt144-120] Caryommida = Astrosphærida multiplica = Polysphæria polyacantha.

[Nt145-121] Caryomma = Nut-eye; κάρυον, ὄμμα.

[Nt146-122] Arachnopila = Cobweb ball; ἀράχνη, πῖλος.

[Nt147-123] Arachnopegma = Cobweb-building; ἀράχνη, πῆγμα.

[Nt148-124] Arachnosphæra = Cobweb-sphere; ἀράχνη, σφαῖρα.

[Nt149-125] Spongiommida = Astrosphærida spongiosa = Spongosphærida polyacantha.

[Nt150-126] Spongiomma = Spongy-eye; σπόγγια, ὄμμα.

[Nt151-127] Spongodrymus = Spongy wood; σπόγγος, δρῦμος.

[Nt152-128] Spongechinus = Spongy Urchin; σπόγγος, ἐχῖνος.

[Nt153-129] Spongothamnus = Spongy shrub; σπόγγος, θάμνος.

[Nt154-130] Spongopila = Spongy ball; σπόγγος, πῖλος.

[Nt155-131] Rhizoplegma = Root-shaped wicker-work; ῥῖζα, πλέγμα.

[Nt156-132] Lychnosphæra = Lantern-sphere; λύχνος, σφαῖρα.

[Nt157-133] Centrocubus = Shell with a central cube; κέντρον, κῦβος.

[Nt158-134] Octodendron = Shell with eight trees; ὄκτω, δένδρον.

[Nt159-135] Spongosphæra = Spongy sphere; σπόγγος, σφαῖρα.

[Nt160-136] Rhizosphæra = Root-sphere; ῥῖζα, σφαῖρα.

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