The great family of blennies, Blenniidæ, contains a vast number of species with elongate body, numerous dorsal spines, without suborbital stay or sucking-disk, and the ventrals jugular, where present, and of one spine and less than five soft rays. Most of them are of small size, living about rocks on the sea-shores of all regions. In general they are active fishes, of handsome but dark coloration, and in the different parts of the group is found great variety of structure. The tropical forms differ from those of arctic regions in the much shorter bodies and fewer vertebræ. These forms are most like ordinary fishes in appearance and structure and are doubtless the most primitive. Of the five hundred known species of blennies, we can note only a few of the most prominent. To Clinus and related genera belong many species of the warm seas, scaly and ovoviviparous, at least for the most part. The largest of these is the great kelpfish of the coast of California, Heterostichus rostratus, a food-fish of importance, reaching the length of two feet. Others of this type scarcely exceed two inches. Neoclinus satiricus, also of California, is remarkable for the great length of the upper jaw, which is formed as in Opisthognathus. Its membranes are brightly colored, being edged with bright yellow. Gibbonsia elegans is the pretty "señorita" of the coralline-lined rock-pools of California. Lepisoma nuchipinne, with a fringe of filaments at the nape, is very abundant in rock-pools of the West Indies. The species of Auchenopterus abound in the rock-pools of tropical America. These are very small neatly colored fishes with but one soft ray in the long dorsal fin. Species of Tripterygion, Myxodes, Cristiceps, and other genera abound in the South Pacific.

In Blennius and its relatives the body is scaleless and the slender teeth are arranged like the teeth of a comb. In most species long, fang-like posterior canines are developed in the jaws. Blennius is represented in Europe by many species, Blennius galerita, ocellaris, and basiliscus being among the most common. Certain species inhabit Italian lakes, having assumed a fresh-water habit. The numerous American species mostly belong to other related genera, Chasmodes bosquianus being most common. Blennius yatabei abounds in Japan. In Petroscirtes and its allies the gill-openings are much restricted. The species are mainly Asiatic and Polynesian and are very prettily colored. Petroscirtes elegans and P. trossulus adorn the Japanese rock-pools and others, often deep blue in color, abound in the coral reefs of Polynesia.

The rock-skippers (Salarias, Alticus, etc.) are herbivorous, with serrated teeth set loosely in the jaws. These live in the rock-pools of the tropics and leap from rock to rock when disturbed with the agility of lizards. They are dusky or gray in color with handsome markings. One of them, Erpichthys or Alticus saliens in Samoa, lives about lava rocks between tide-marks, and at low tide remains on the rocks, over which it runs with the greatest ease and with much speed, its movements being precisely like those of Periophthalmus. As in the species of the latter genus, otherwise wholly different, this Alticus has short ventral fins padded with muscle.

Erpichthys atlanticus is found in abundance on both coasts of tropical America. Many species abound in Polynesia and in both Indies. Salarias enosimæ lives in the clefts of lava rocks on the shores of Japan. Ophioblennius (webbi) is remarkable for its strong teeth, Emblemaria (nivipes, Atlantica) for its very high dorsal. Many other genera allied to Blennius, Clinus, and Salarias abound in the warm seas.

The Northern Blennies: Xiphidiinæ, Stichæiniæ, etc.—The blennies of the north temperate and arctic zones have the dorsal fin more elongate, the dorsal fin usually but not always composed entirely of spines. The scales are small and the ventral fins generally reduced in size. These are divided by Dr. Gill into several distinct families, but the groups recognized by him are subject to intergradations.

Chirolophis (ascanii) of north Europe is remarkable for the tufted filaments on the head. These are still more developed in Bryostemma of the North Pacific, Bryostemma polyactocephalum and several other species being common from Puget Sound to Japan. Apodichthys (flavidus) of California is remarkable for a large quill-shaped anal spine and for the great variation in color, the hue being yellow, grass-green, or crimson, according to the color of the algæ about it. There is no evidence, however, that the individual fish can change its color, and these color forms seem to be distinct races within the species. Xererpes fucorum of California lies quiescent in the seaweed (Fucus) after the tide recedes, its form, color, and substance seeming to correspond exactly with those of the stems of algæ. Pholis gunnellus is the common gunnel (gunwale), or butter-fish, of both shores of the North Atlantic, with numerous allies in the North Pacific. Of these, Enedrias nebulosus, the ginpo, or silver-tail, is especially common in Japan. Xiphidion and Xiphistes of the California coast, and Dictyosoma of Japan, among others, are remarkable for the great number of lateral lines, these extending crosswise as well as lengthwise. Cebedichthys violaceus, a large blenny of California, has the posterior half of the dorsal made of soft rays. Opisthocentrus of Siberia and north Japan has the dorsal spines flexible, only the posterior ones being short and stiff. The snake-blennies (Lumpenus), numerous in the far North, are extremely slender, with well-developed pectorals and ventrals. Lumpenus lampetræformis is found on both shores of the Atlantic. In Stichæus a lateral line is present. There is none in Lumpenus, and in Ernogrammus and Ozorthe there are three. All these are elongate fishes, of some value as food and especially characteristic of the Northern seas. Fossil blennies are almost unknown. Pterygocephalus paradoxus of the Eocene resembles the living Cristiceps, a genus which differs from Clinus in having the first few dorsal spines detached, inserted on the head. The first spine alone in Pterygocephalus is detached and is very strong. A species called Clinus gracilis is described from the Miocene near Vienna, Blennius fossilis from the Miocene of Croatia, and an uncertain Oncolepis isseli from Monte Bolca. The family is certainly one of the most recent in geologic times. The family of Blenniidæ, as here recognized, includes a very great variety of forms and should perhaps be subdivided into several families, as Dr. Gill has suggested. At present there is, however, no satisfactory basis of division known.

The Quillfishes: Ptilichthyidæ.—The Ptilichthyidæ, or quillfishes, are small and slender blennies of the North Pacific, with very numerous fin-rays. Ptilichthys goodei has 90 dorsal spines and 145 soft rays. Another group of very slender naked blennies is the small family of Xiphasiidæ from the South Pacific. The jaws have excessively long canines; there are no ventral fins. The dorsal fin is very high and the caudal ends in a long thread.

The Blochiidæ.—Of doubtful relationship is the extinct family of Blochiidæ. In this group the body is elongate, covered with keeled plates imbricated like shingles. The dorsal is composed of many slender spines, and the vertebræ much elongate. In Blochius longirostris (Monte Bolca Eocene) has very long jaws, lined with small teeth. Zittel regards the family as allied to the Belonorhynchidæ, but the prolongation of the jaws may be a character of analogy merely. Woodward places it next to the Blenniidæ, supposing it to have small and jugular ventral fins. But as the presence of ventral fins is uncertain, the position of the family cannot be ascertained and it may really belong in the neighborhood of Ammodytes. The dorsal rays are figured by Woodward as simple.

The Patæcidæ etc.—The Patæcidæ are blenny-like fishes of Australia, having the form of Congriopus, the spinous dorsal being very high and inserted before the eyes, forming a crest. Patæcus fronto is not rare in South Australia. The Gnathanacanthidæ is another small group of peculiar blennies from the Pacific. The Acanthoclinidæ are small blennies of New Zealand with numerous spines in the anal fin. Acanthoclinus littoreus is the only known species.

The Gadopsidæ, etc.—The family of Gadopsidæ of the rivers of New Zealand and southern Australia consists of a single species, Gadopsis marmoratus, resembling the scaly blennies called Clinus, but with long ventrals of a single ray, and three spines in the anal fin besides other peculiarities. The species is locally very common and with various other fishes in regions where true trout are unknown, it is called "trout."

The Cerdalidæ are small band-shaped blennies of the Pacific coast of Panama. The slender dorsal spines pass gradually into soft rays. Three species are known.

The wrymouths, or Cryptacanthodidæ, are large blennies of the northern seas, with the mouth almost vertical and the head cuboid. The wrymouth or ghostfish, Cryptacanthodes maculatus, is frequently taken from Long Island northward. It is usually dusky in color, but sometimes pure white. Other genera are found in the north Pacific.

The Wolf-fishes: Anarhichadidæ.—The wolf-fishes (Anarhichadidæ) are large blennies of the northern seas, remarkable for their strong teeth. Those in front are conical canines. Those behind are coarse molars. The dorsal is high, of flexible spines. The species are large, powerful, voracious fishes, known as wolf-fishes. Anarhichas lupus is the common wolf-fish of the north Atlantic, reaching a length of four to six feet, the body marked by dark cross-bands. Other similar species are found both in the north Pacific and north Atlantic. Anarhichas lepturus, plain brown in color, is common about the Aleutian Islands.

In the wolf-eel (Anarrhichthys ocellatus) of the coast of California, the head is formed as in Anarhichas but the body is band-shaped, being drawn out into a very long and tapering tail. This species, which is often supposed to be a "sea-serpent," sometimes reaches a length of eight feet. It is used for food. It feeds on sea-urchins and sand-dollars (Echinarachinius) which it readily crushes with its tremendous teeth.

The skull of a fossil genus, Laparus (alticeps), with a resemblance to Anarhichas, is recorded from the Eocene of England.

The Eel-pouts: Zoarcidæ.—The remaining blenny-like forms lack fin spines, agreeing in this respect with the codfishes and their allies. In all of the latter, however, the hypercoracoid is imperforate, the pseudobranchiæ are obsolete, and the tail isocercal. The forms allied to Zoarces and Ophidion, and which we may regard as degraded blennies, have homocercal (rarely leptocercal) tails, generally but not always well-developed pseudobranchiæ and the usual foramen in the hypercoracoid.

The Zoarcidæ, or eel-pouts, have the body elongate, naked, or covered with small scales, the dorsal and anal of many soft rays and the gill-openings confined to the side. Most of the species live in rather deep water in the Arctic and Antarctic regions. Zoarces viviparus, the "mother of eels," is a common fish of the coasts of northern Europe. In the genus Zoarces, the last rays of the dorsal are short and stiff, like spines. The species are viviparous; the young being eel-like in form, the name "mother of eels" has naturally arisen in popular language. The American eel-pout, sometimes called mutton-fish, Zoarces anguillaris, is rather common north of Cape Cod, and a similar species, Zoarces elongatus, is found in northern Japan. Lycodopsis pacifica, without spines in the dorsal, replaces Zoarces in California. The species of Lycodes, without spines in the dorsal, and with teeth on the vomer and palatines, are very abundant in the northern seas, extending into deep waters farther south. Lycodes reticulatus is the most abundant of these fishes, which are valued chiefly by the Esquimaux and other Arctic races of people. Numerous related genera are recorded from deep-sea explorations, and several others occur about Tierra del Fuego. Gymnelis, small, naked species brightly colored, is represented by Gymnelis viridis in the Arctic and by Gymnelis pictus about Cape Horn.

The family of Scytalinidæ contains a single species, Scytalina cerdale, a small snake-shaped fish which lives in wet gravel between tide-marks, on Waada Island near Cape Flattery in Washington, not having yet been found elsewhere. It dives among the wet stones with great celerity, and can only be taken by active digging.

To the family of Congrogadidæ belong several species of eel-shaped blennies with soft rays only, found on the coasts of Asia. Another small family, Derepodichthyidæ, is represented by one species, a scaleless little fish from the shores of British Columbia.

The Xenocephalidæ consist of a single peculiar species, Xenocephalus armatus, from the island of New Ireland. The head is very large, helmeted with bony plates and armed with spines. The body is short and slender, the ventrals with five rays, the dorsal and anal short.

The Cusk-eels: Ophidiidæ.—The more important family of Ophidiidæ, or cusk-eels, is characterized by the extremely anterior position of the ventral fins, which are inserted at the throat, each one appearing as a long forked barbel. The tail is leptocercal, attenuate, the dorsal and anal confluent around it. Ophidion barbatum and Rissola rochei are common in southern Europe. Rissola marginata is the commonest species on our Atlantic coast, and Chilara taylori in California. Other species are found farther south, and still others in deep water. Genypterus contains numerous species of the south Pacific, some of which reach the length of five feet, forming a commercial substitute for cod. Genypterus capensis is the klipvisch of the Cape of Good Hope, and Genypterus australis the "Cloudy Bay cod" or "rock ling" of New England. Another large species, Genypterus maculatus, occurs in Chile. A few fragments doubtfully referred to Ophidion and Fierasfer occur in the Eocene and later rocks. The Lycodapodidæ contain a few small, scaleless fishes (Lycodapus) dredged in the north Pacific.

Sand-lances: Ammodytidæ.—Near the Ophidiidæ are placed the small family of sand-lances (Ammodytidæ). This family comprises small, slender, silvery fishes, of both Arctic and tropical seas, living along shore and having the habit of burying themselves in the sand under the surf in shallow water. The jaws are toothless, the body scarcely scaly and crossed by many cross-folds of skin, the many-rayed dorsal fin is without spines, and the ventral fins when present are jugular. The species of the family are very much alike. From their great abundance they have sometimes much value as food, more perhaps as bait, still more as food for salmon and other fishes, from which they escape by plunging into the sand. Sometimes a falling tide leaves a sandy beach fairly covered with living "lants" looking like a moving foam of silver. Ammodytes tobianus is the sand-lance or lant of northern Europe. Ammodytes americanus, scarcely distinguishable, replaces it in America; and Ammodytes personatus in California, Alaska, and Japan. This is a most excellent pan fish, and the Japanese, who regard little things, value it highly.

In the genus Hyperoplus there is a large tooth on the vomer. In the tropical genera there is a much smaller number of vertebræ and the body is covered with ordinary scales instead of delicate, oblique cross-folds of skin. These tropical species must probably be detached from the Ammodytidæ to form a distinct family, Bleekeriidæ. Bleekeria kallolepis is found in India, Bleekeria gilli is from an unknown locality, and the most primitive species of sand-lance, Embolichthys mitsukurii, occurs in Formosa. In this species, alone of the sand-lances, the ventral fins are retained. These are jugular in position, as in the Zoarcidæ, and the rays are I, 3. The discovery of this species makes it necessary to separate the Ammodytidæ and Bleekeriidæ widely from the Percesoces, and especially from the extinct families of Crossognathidæ and Cobitopsidæ with which its structure in other regards has led Woodward, Boulenger, and the present writer to associate it.

Although an alleged sand-lance, Rhynchias septipinnis, with ventral fins abdominal, was described a century ago by Pallas, no one has since seen it, and it may not exist, or, if it exists, it may belong among the Percesoces. The relation of Ammodytes to Embolichthys is too close to doubt their close relationship. According to Dr. Gill the Ammodytidæ belong near the Hemerocœtidæ.

The Pearlfishes: Fierasferidæ.—In the little group of pearlfishes, called Fierasferidæ or Carapidæ, the body is eel-shaped with a rather large head, and the vent is at the throat. Numerous species of Fierasfer (Carapus) are found in the warm seas. These little fishes enter the cavities of sea-cucumbers (Holothurians) and other animals which offer shelter, being frequently taken from the pearl-oyster. In the Museum of Comparative Zoology, according to Professor Putnam, is "one valve of a pearl-oyster in which a specimen of Fierasfer dubius is beautifully inclosed in a pearly covering deposited on it by the oyster." A photograph of a similar specimen is given above. The species found in Holothurians are transparent in texture, with a bright pearly luster. Species living among lava rocks, as Jordanicus umbratilis of the south seas, are mottled black. Since this was written a specimen of this black species has been obtained from a Holothurian in Hilo, Hawaii, by Mr. H. W. Henshaw.

The Brotulidæ.—The Brotulidæ constitute a large family of fishes, resembling codfishes, but differing in the character of the hypercoracoid, as well as in the form of the tail. The resemblance between the two groups is largely superficial. We may look upon the Brotulidæ as degraded blennies, but the Gadidæ have an earlier and different origin which has not yet been clearly made out. Most of the Brotulidæ live in deep water and are without common name or economic relations. Two species have been landlocked in cave streams in Cuba, where they have, like other cavefishes, lost their sight, a phenomenon which richly deserves careful study, and which has been recently investigated by Dr. C. H. Eigenmann. These blind Brotulids, called Pez Ciego in Cuba, are found in different caves in the county of San Antonio, where they reach a length of about five inches. As in other blindfishes, the body is translucent and colorless. These species are known as Lucifuga subterranea and Stygicola dentata. They are descended from allies of the genera called Brotula and Dinematichthys. Brotula barbata is a cusk-like fish, occasionally found in the markets of Havana. Similar species, Brotula multibarbata and Sirembo inermis, are common in Japan, and Brosmophycis marginatus, beautifully red in color, is occasionally seen on the coast of California. Many other genera and species abound in the depths of the sea and in crevices of coral reefs, showing much variety in form and structure.

The Bregmacerotidæ are small fishes, closely related to the Brotulids, having the hypercoracoid perforate, but with several minor peculiarities, the first ray of the dorsal being free and much elongate. They live near the surface in the open sea. Bregmaceros macclellandi is widely diffused in the Pacific.

Ateleopodidæ.—The small family of Ateleopodidæ includes long-bodied, deep-water fishes of the Pacific, resembling Macrourus, but with smooth scales. The group has the coracoids as in Brotulidæ, and the actinosts are united in an undivided plate. Ateleopus japonicus is the species taken in Japan.

Suborder Haplodoci.—We may here place the peculiar family of Batrachoididæ, or toadfishes. It constitutes the suborder of Haplodoci (ἁπλόος, simple; δόκος, shaft) from the simple form of the post-temporal. This order is characterized by the undivided post-temporal bone and by the reduction of the gill-arches to three. A second bone behind the post-temporal connects the shoulder-girdle above to the vertebral column. The coracoid bones are more or less elongate, suggesting the arm seen in pediculate fishes.

The single family has the general form of the Cottidæ, the body robust, with large head, large mouth, strong teeth, and short spinous dorsal fin. The shoulder-girdle and its structures differ little from the blennioid type. There are no pseudobranchiæ and the tail is homocercal. The species are relatively few, chiefly confined to the warm seas and mostly American, none being found in Europe or Asia. Some of them ascend rivers, and all are carnivorous and voracious. None are valued as food, being coarse-grained in flesh. The group is probably nearest allied to the Trachinidæ or Uranoscopidæ.

Opsanus tau, the common toadfish, or oyster-fish, of our Atlantic coast, is very common in rocky places, the young clinging to stones by a sucking-disk on the belly, a structure which is early lost. It reaches a length of about fifteen inches. Opsanus pardus, the leopard toadfish, or sapo, of the Gulf coast, lives in deeper water and is prettily marked with dark-brown spots on a light yellowish ground.

In Opsanus the body is naked and there is a large foramen, or mucous pore, in the axil of the pectoral. In the Marcgravia cryptocentra, a large Brazilian toadfish, this foramen is absent. In Batrachoides, a South American genus, the body is covered with cycloid scales. Batrachoides surinamensis is a common species of the West Indies. Batrachoides pacifici occurs at Panama. The genus Porichthys is remarkable for the development of series of mucous pores and luminous spots in several different lateral lines which cover the body. These luminous spots are quite unlike those found in the lantern-fishes (Myctophidæ) and other Iniomi. Their structure has been worked out in detail by Dr. Charles Wilson Greene, a summary of whose conclusions are given on page 191, Vol. I.

The common midshipman, or singing fish, of the coast of California is Porichthys notatus. This species, named midshipman from its rows of shining spots like brass buttons, is found among rocks and kelp and makes a peculiar quivering or humming noise with its large air-bladder.

Porichthys porosissimus, the bagre sapo, is common on all coasts of the Gulf of Mexico and the Caribbean Sea. Porichthys margaritatus is found about Panama and Porichthys porosus in Chile.

The species of Thalassophryne and Thalassothia, the poison toadfishes, are found along the coasts of South America, where they sometimes ascend the rivers. In these species there is an elaborate series of venom glands connected with the hollow spines of the opercle and the dorsal spines. Dr. Günther gives the following account of this structure as shown in Thalassophryne reticulata, a species from Panama:

"In this species I first observed and closely examined the poison organ with which the fishes of this genus are provided. Its structure is as follows: (1) The opercular part: The operculum is very narrow, vertically styliform and very mobile; it is armed behind with a spine, eight lines long in a specimen of 10½ inches, and of the same form as the venom fang of a snake; it is, however, somewhat less curved, being only slightly bent upward. It has a longish slit at the outer side of its extremity which leads into a canal perfectly closed and running along the whole length of its interior; a bristle introduced into the canal reappears through another opening at the base of the spine, entering into a sac situated on the opercle and along the basal half of the spine; the sac is of an oblong-ovate shape and about double the size of an oat grain. Though the specimen had been preserved in spirits for about nine months it still contained a whitish substance of the consistency of thick cream, which on the slightest pressure freely flowed from the opening in the extremity of the spine. On the other hand, the sac could be easily filled with air or fluid from the foramen of the spine. No gland could be discovered in the immediate neighborhood of the sac; but on a more careful inspection I found a minute tube floating free in the sac, whilst on the left-hand side there is only a small opening instead of the tube. The attempts to introduce a bristle into this opening for any distance failed, as it appears to lead into the interior of the basal portion of the operculum, to which the sac firmly adheres at this spot. (2) The dorsal part is composed of the two dorsal spines, each of which is ten lines long. The whole arrangement is the same as in the opercular spines; their slit is at the front side of the point; each has a separate sac, which occupies the front of the basal portion; the contents were the same as in the opercular sacs, but in somewhat greater quantity. A strong branch of the lateral line ascends to the immediate neighborhood of their base. Thus we have four poison spines, each with a sac at its base; the walls of the sacs are thin, composed of a fibrous membrane, the interior of which is coated over with mucus. There are no secretory glands embedded between these membranes, and these sacs are probably merely the reservoirs in which the fluid secreted accumulates. The absence of a secretory organ in the immediate neighborhood of the reservoirs (an organ the size of which would be in accordance with the quantity of fluid secreted), the diversity of the osseous spines which have been modified into poison organs, and the actual communication indicated by the foramen in the sac lead me to the opinion that the organ of secretion is either that system of muciferous channels which is found in nearly the whole class of fishes, and the secretion of which has poisonous qualities in a few of them, or at least an independent portion of it. This description was made from the first example; through the kindness of Captain Dow I received two other specimens, and in the hope of proving the connection of the poison bags with the lateral-line system, I asked Dr. Pettigrew, of the Royal College of Surgeons, a gentleman whose great skill has enriched that collection with a series of the most admirable anatomical preparations, to lend me his assistance in injecting the canals. The injection of the bags through the opening of the spine was easily accomplished; but we failed to drive the fluid beyond the bag or to fill with it any other part of the system of muciferous channels. This, however, does not disprove the connection of the poison bags with that system, inasmuch as it became apparent that if there be minute openings they are so contracted by the action of the spirit in which the specimens were preserved as to be impassable to the fluid of injection. A great part of the lateral-line system consists of open canals; however, on some parts of the body, these canals are entirely covered by the skin; thus, for instance, the open lateral line ceases apparently in the suprascapular region, being continued in the parietal region. We could not discover any trace of an opening by which the open canal leads to below the skin; yet we could distinctly trace the existence of the continuation of the canal by a depressed line, so that it is quite evident that such openings do exist, although they may be passable only in fresh specimens. Thus likewise the existence of openings in the bags, as I believed to have found in the first specimen dissected, may be proved by examination of fresh examples. The sacs are without an external muscular layer and situated immediately below the loose thick skin which envelops their spines to their extremity. The injection of the poison into a living animal, therefore, can only be effected by the pressure to which the sac is subjected the moment the spine enters another body. Nobody will suppose that a complicated apparatus like the one described can be intended for conveying an innocuous substance, and therefore I have not hesitated to designate it as poisonous; and, Captain Dow informs me in a letter lately received, 'the natives of Panama seemed quite familiar with the existence of the spines and of the emission from them of a poison which, when introduced into a wound, caused fever, an effect somewhat similar to that produced by the sting of a scorpion; but in no case was a wound caused by one of them known to result seriously. The slightest pressure of the finger at the base of the spine caused the poison to jet a foot or more from the opening of the spine.' The greatest importance must be attached to this fact, inasmuch as it assists us in our inquiries into the nature of the functions of the muciferous system, the idea of its being a secretory organ having lately been superseded by the notion that it serves merely as a stratum for the distribution of peripheric nerves. Also the objection that the sting-rays and many Siluroid fishes are not poisonous because they have no poison organ cannot be maintained, although the organs conveying their poison are neither so well adapted for this purpose nor in such a perfect connection with the secretory mucous system as in Thalassophryne. The poison organ serves merely as a weapon of defense. All the Batrachoids with obtuse teeth on the palate and in the lower jaw feed on Mollusca and Crustaceans."

No fossil Batrachoididæ are known.

Suborder Xenopterygii.—The clingfishes, forming the suborder Xenopterygii (ξενός, strange; πτερύξ, fin), are, perhaps, allied to the toadfishes. The ventral fins are jugular, the rays I, 4 or I, 5, and between them is developed an elaborate sucking-disk, not derived from modified fins, but from folds of the skin and underlying muscles.

The structure of this disk in Gobiesox sanguineus is thus described by Dr. Günther:

"The whole disk is exceedingly large, subcircular, longer than broad, its length being (often) one-third of the whole length of the fish. The central portion is formed merely by skin, which is separated from the pelvic or pubic bones by several layers of muscles. The peripheric portion is divided into an anterior and posterior part by a deep notch behind the ventrals. The anterior peripheric portion is formed by the ventral rays, the membrane between them and a broad fringe which extends anteriorly from one ventral to the other. This fringe is a fold of the skin, containing on one side the rudimentary ventral spine, but no cartilage. The posterior peripheric portion is suspended on each side on the coracoid, the upper bone of which is exceedingly broad, becoming a free, movable plate behind the pectoral. The lower bone of the coracoid is of a triangular form, and supports a very broad fold of the skin, extending from one side to the other, and containing a cartilage which runs through the whole of that fold. Fine processes of the cartilage are continued into the soft striated margin, in which the disk terminates posteriorly. The face of the disk is coated with a thick epidermis, like the sole of the foot in higher animals. The epidermis is divided into many polygonal plates. There are no such plates between the roots of the ventral fins."

The body is formed much as in the toadfishes. The skin is naked and there is no spinous dorsal fin. The skeleton shows several peculiarities; there is no suborbital ring, the palatine arcade is reduced, as are the gill-arches, the opercle is reduced to a spine-like projection, and the vertebræ are numerous. The species are found in tide-pools in the warm seas, where they cling tightly to the rocks with their large ventral disks.

Several species of Lepadogaster and Mirbelia are found in the Mediterranean. Lepadogaster gouani is the best-known European species. Aspasma ciconiæ and minima occur about the rocks in the bays of Japan.

Most of the West Indian species belong to Gobiesox, with entire teeth, and to Arbaciosa, with serrated teeth. Some of these species are deep crimson in color, but most of them are dull olive. Gobiesox virgatulus is common on the Gulf Coast. Caularchus mæandricus, a very large species, reaching a length of six inches, abounds along the coast of California. Other genera are found at the Cape of Good Hope, especially about New Zealand. Chorisochismus dentex, from the Cape of Good Hope, reaches the length of a foot.