Page:Scientific results HMS Challenger vol 18 part 1.djvu/360

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,^[1] Haeckel, Prodromus, 1881, pp. 449, 450.

Definition.—Staurosphærida with one single spherical lattice-shell.

Genus 60. Staurosphæra,^[2] 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.

1. Staurostylida = Staurosphærida simplicia = Monosphærida tetracantha.
2. Staurosphæra = Cross-sphere; σταυρός, σφαῖρα.