LANTEKN-FISH. 765 known onlj" by one or a few specimens. The species illustrated upon the accompanying plate are representative ol the range of variety in the group. Thus liathypterois quadri/ilis, remark- able for the four long, whitish filaments of its fins (tactile organs of extreme sensibility), is a little lisli, nearly black, and dwells in the tropical Atlantic at a depth of 500 to 800 fathoms. Another small, dark-culorcd bottom lish (live and une-lialt' inches) is Ipnops Murrayi, found widely distributed at a dei)th of about 2000 fathoms, which is provided with an extraor- dinary sensory apparatus. It is eyeless, but the whole top of the llattened head consists of a pair of large, transparent membrane-bones, which cover a peculiar divided organ, one-half lying on each side of the median line of the head. This at first was supposed to be a luminous organ, but Mosely has discovered that it represents the lost eyes, each lialf of the organ having a flat- tened cornea along the dividing line, and a large retina of complicated structure, adapted to pro- duce an image and to receive especial luminous jays. Referring especially to this fish, Alexander Agassiz has stated that while in some cases the eyes of these migrants from the shores and the surface to the black depths have not been spe- cially modified, in others there have been modi- fications of a luminous mucous membrane, lead- ing on the one hand to phosphorescent organs more or less specialized, or on the other to such remarkable structures as the eyes of Ipnops. intermediate between true eyes and specialized phosphorescent plates. Where the fishes have be- come blind, the integument, lifteral line, and various tactile appendages acquire extraordinary sensil)ility, as in cave animals (q.v. ). The curious miniature of a whale illustrated in Fig. n of the Plate is one of the two known spe- cies of the genus Cetomimus. less than six inches long and living at great depths. For an account of Fig. 8. see I>. cet-Fisii. Laxtebn-Fishes Proper. The foregoing spe- cies do not possess light-giving organs to any considerable degree, if at all : but most of the group are provided with phosphorescent lanterns. The family MyctophidiP contains about 100 spe- cies, all of small size, carnivorous, and very widely distributed in the open seas. They some- times come to the surface at night or in stormy weather, hut ordinarily dwell in the depths. All have luminous spots or photophores more or less regularly placed ahnig the sides of the body, while larger light-giving glands are lodged in the head, or near the tail, or both. One of the most vivid light-bearers is a' steel-blue Pacific Coast species (Tarlctoiihcania teuva), whose light-spots are shown in Fig. 4. It also has large fimc- tional eyes, and creniilated scales, but no lateral line. The name 'viper-fishes' has been given to the genus represented by a species (Chauliodus SInniici) about twelve inches long, discovered on tlio Hanks of Newfoundland. It has both eyes and photophores, and also a tactile ray, extending from the dorsal fin. It is also an inhabitant of the Xorth Pacific. Somewhat similar, and highly endowed with luminous organs, is Photonectrx (jrncilis. known only from a single specimen. 7 inches long, tnken ofT Martinique, 472 fathoms below the surface. Even more extraordinary is the small black fish {]falncofttrufi niri<T) repre- sented in Fig. 10. It lives in very deep water. Jet has large, useful eyes, as well as two 'head- LANTHANUM. lights' in the form of strong luminous organs- near the eyes, and many photophores on the body. The curious way in which the lower jaw is at- tached to the skull is unique among fishes. This coinieetion is made by a cylindrical muscular baud, which Gunther believes to be contractile, "serving to give the extremity of the mandible power of resistance when the fish has seized its prey,"' as without such a contrivance .so long and slender a bone as the jaw would be broken by the victim's struggles. ArgyrojHdecus (Fig. 7) represents a group of fishes, only two or three inches long, that come to the surface at night, and during the day descend into the depths. Consult the general authorities mentioned under Fisii, and especially Goode and Bean, Oceanic Ichthyology (Cambridge, 1890), where complete references to the literature relating to deep-sea fishes will be found. Se? Deep-Sea E.x.ploratiox for the methods by which many of these fishes have been obtained; and LiJiixosiTY of Animals for a more par- ticular account of their light-giving organs. LANTERN-rLY. An insect of the exten- sive family Fulgoridie. Some of these insects are among the largest known, but others are quite small. Some look very much like butter- flies or moths, while still others greatly resemble Xeuroptera. The family has received its com- mon name because of the peculiarly enlarged, mis- shapen proboscis of some of the tropical forms, which may equal the length of the body, and is said by the natives of the tropics to be lu- minescent — a statement disputed by scientific observers. Many of the species are beautifully and brilliantly colored. Some of them secrete a valuable white wax, in some eases in masses far exceeding the length of the insect. This is col- lected by the Chinese from a local species and made into candles. All the lantern-flies are her- bivorous. Some of the exotic species seriously injure crojis. but none in the United States does any appreciable damage. They are common in rank herbage and among the reeds of fresh and salt water swamps, and are usually protectively colored. Several forms that are green in summer turn brown with the reeds in the autumn. A pale green species (Orinrnis xcplcittrionalis) occurs on the wild grapevine. .Scolops is a very com- mon, widely distributed North American genus, with a long proboscis like that of the exotic species. The most injurious of the Xorth Ameri- can species is Chlorochroa conica, which feeds on the leaves of corn and the sugar-beet in parts of the West. liANTERN-SHEIX. A bivalve mollusk of the genus Anatina. The shell is oblong, swollen thin, often inequivalve. The species occur in India, the Philippines, Xew Zealand, and on the west coast of America. LANTHANUM (Neo-Lat., from Gk. Xai-- BaKif, lanlhriiicin, to conceal). A metallic ele- ment discovered in 18o0 by Mosander in the mineral cerite. Absolutely pure lanthanum has probably never lieen obtained. Resides cerite. lanthanum occurs also in the minerals gadolin- ite, lanthanite, and orthite. The ordinary proc- esses for its isolation from the substances with which it is associated are verj- complex. From its chloride it may be obtained in the metallic state by treatment with metallic potassium. Lan- thanum (symbol, La; atomic weight, 133) is a
