The Mailed-cheek Fishes.—The vast group of Pareioplitæ (Loricati) or mailed-cheek fishes is characterized by the presence of a "bony stay" or backward-directed process from the third suborbital. This extends backward across the cheek toward the preopercle. In the most generalized forms this bony stay is small and hidden under the skin. In more specialized forms it grows larger, articulates with the preopercle, and becomes rough or spinous at its surface. Finally, it joins the other bones to form a coat of mail which covers the whole head. In degenerate forms it is again reduced in size, finally becoming insignificant.

The more primitive Pareioplitæ (παρεία, cheek; ὁπλιτής, armed) closely resemble the Percomorphi, having the same fins, the same type of shoulder-girdle, and the same insertion of the ventral fins. In the more specialized forms the ventral fins remain thoracic, but almost all other parts of the anatomy are greatly distorted. In all cases, so far as known to the writer, the hypercoracoid is perforate as in the Percomorphi. There are numerous points of resemblance between the Cirrhitidæ and the Scorpænidæ, and it is probable that the Scorpænidæ with all the other Pareioplitæ sprang from some perciform stock allied to Cirrhitidæ and Latrididæ.

Fossil mailed-cheek fishes are extremely few and throw little light on the origin of the group. Those belong chiefly to the Cottidæ. Lepidocottus, recorded from the Miocene and Oligocene, seems to be the earliest genus.

The Scorpion-fishes: Scorpænidæ.—The vast family of Scorpænidæ, or scorpion-fishes, comprises such a variety of forms as almost to defy diagnosis. The more primitive types are percoid in almost all respects, save in the presence of the subocular stay. Their scales are ctenoid and well developed. The dorsal spines are numerous and strong. The ventral fins are complete and normally attached; the anal has three strong spines. The cranium shows only a trace of spiny ridges, and the five spines on the preoperculum are not very different from those seen in some species of bass. The gill-arches are, however, different, there being but 3½ gills and no slit behind the last. Otherwise the mouth and pharanx show no unusual characters. In the extremes of the group, however, great changes take place, the head becomes greatly distorted with ridges and grooves, the anal spines are lost, and the dorsal spines variously modified. The scales may be lost or replaced by warts or prickles and the ventral fins may be greatly reduced. Still the changes are very gradual, and it is not easy to divide the group into smaller families.

The most primitive existing genus is doubtless Sebastes. The familiar rosefish, Sebastes marinus, is found on both shores of the north Atlantic. It is bright red in color and is valued as food. As befits a northern fish, it has an increased number of vertebræ (31) and the dorsal spines number 15. From its large haddock-like eye it has been called the Norway haddock. It is an important food-fish in New England as well as in northern Europe.

In the north Pacific Sebastes gives place to Sebastolobus, with three species (macrochir, altivelis, and alascanus), all bright-red fishes of soft substance and living in rather deep water. Sebastolobus is characterized by its two-lobed pectoral fin, the lower rays being enlarged.

The genus Sebastodes, with its rougher-headed ally Sebastichthys, with 13 dorsal spines and the vertebræ 27, ranges farther south than Sebastes and forms one of the most characteristic features of the fauna of California and Japan, 50 species occurring about California and 25 being already known from Japan. One species (Sebastichthys capensis) is recorded from the Cape of Good Hope, and two, Sebastichthys oculatus and S. darwini, from the coast of Chile.

Within the limits of Sebastodes and Sebastichthys is a very large range of form and color, far more than should exist within the range of a natural genus. On the other hand, all attempts at generic subdivision have failed because the species form a number of almost perfectly continuous series. At one extreme are species with large mouths, small scales, relatively smooth cranium, and long gill-rakers. At the other extreme are robust species, with the head very rough, the mouth moderate, the scales larger, and the gill-rakers short and thick. Still other species have slender cranial spines and spots of bright pink in certain specialized localities. These approach the genus Helicolenus as other species approach Scorpæna.

The various species are known in California as rockfish, or rock-cod, in Japan as Soi and Mebaru. In both regions they form a large part of the bulk of food-fishes, the flesh being rather coarse and of moderate flavor. All the species so far as known are ovoviviparous, the young being brought forth in summer in very great number, born at the length of about ¼ of an inch. The species living close to shore are brown, black, or green. Those living in deeper waters are bright red, and in still deeper waters often creamy or gray, with the lining of the mouth and the peritoneum black. The largest species reach a length of two or three feet, the smallest eight or ten inches. None are found between Lower California and Peru and none south of Nagasaki in Japan. Of the California species the following are of most note: Sebastodes paucispinis, the Bocaccio of the fishermen, from its large mouth, is an elongate fish, dull red in color, and reaching a very large size. In deeper waters are Sebastodes jordani and Sebastodes goodei, the former elongate and red, the latter more robust and of a very bright crimson color. Sebastodes ovalis, the viuva, and Sebastodes entomelas are grayish in hue, and the related Sebastodes proriger is red. The green rockfish Sebastodes flavidus is common along the shore, as also the black rockfish, known as pêche prêtre or priestfish, Sebastodes mystinus. Less common is Sebastodes melanops. Similar to this but more orange in color is the large Sebastodes miniatus. Somewhat rougher-headed is the small grass rockfish, Sebastodes atrovirens. On the large red rockfish, Sebastichthys ruberrimus, the spinous ridges are all large and rough serrate. On the equally large Sebastichthys levis these ridges are smooth. Both these species are bright red in color. Sebastichthys rubrovinctus, called the Spanish-flag, is covered with broad alternating bands of deep crimson and creamy pink. It is the most handsomely colored of our marine fishes and is often taken in southern California. Sebastichthys elongatus is a red species with very large mouth. Several other species small in size are red, with three or four spots of bright pink. The commonest of these is the corsair, Sebastichthys rosaceus, plain red and golden. Another species is the green and red flyfish, Sebastichthys rhodochloris. Sebastichthys constellatus is spotted with pink and Sebastichthys chlorostictus with green. To this group with pink spots the South American and African species belong, but none of the Japanese. Sebastodes aleutianus is a large red species common in Alaska and Sebastodes ciliatus a green one. About the wharves in California and northward the brown species called Sebastichthys auriculatus is abundant. In the remaining species the spinous ridges are progressively higher, though not so sharp as in some of those already named. Sebastichthys maliger has very high dorsal spines and a golden blotch on the back. In Sebastichthys caurinus and especially Sebastichthys vexillaris the spines are very high, but the coloration is different, being reddish brown. Sebastichthys nebulosus is blue-black with golden spots. Sebastichthys chrysomelas is mottled black and yellow. Sebastichthys carnatus is flesh-color and green. Sebastichthys rastrelliger is a small, blackish-green species looking like Sebastodes atrovirens, but with short gill-rakers. Sebastichthys hopkinsi and Sebastichthys gilberti are small species allied to it. The treefish, Sebastichthys serriceps, has very high spines on the head, and the olive body is crowned by broad black bands. Still more striking is the black-banded rockfish, Sebastichthys nigrofasciatus, with very rough head and bright red body with broad cross-bands of black.

Of the Japanese species the commonest, Sebastodes inermis, the Mebaru, much resembles Sebastodes flavidus. Sebastodes fuscescens looks like Sebastodes melanops, as does also Sebastodes taczanowskii. Sebastodes matsubaræ and S. flammeus and S. iracundus, bright-red off-shore species, run close to Sebastodes aleutianus. Sebastichthys pachycephalus suggests Sebastichthys chrysomelas. Sebastodes steindachneri and S. itinus are brighter-colored allies of Sebastodes ovalis and Sebastodes scythropus and Sebastodes joyneri represent Sebastodes proriger. Sebastichthys trivittatus, green, striped with bright golden, bears some resemblance to Sebastichthys maliger. Sebastichthys elegans, Sebastichthys oblongus, and Sebastichthys mitsukurii, dwarf species, profusely spotted, have no analogues among the American forms. Sebastodes glaucus of the Kurile Islands has 14 dorsal spines and is not closely related to any other. Fourteen dorsal spines are occasionally present in Sebastichthys elegans. All the other species show constantly 13.

The genus Sebastiscus has the general appearance of Sebastodes, and like the latter possesses a large air-bladder. It however agrees with Scorpæna in the possession of but 12 dorsal spines and 24 vertebræ. The two known species are common in Japan. Sebastiscus marmoratus, mottled brown, is everywhere abundant along the coast, and the pretty Sebastiscus albofasciatus, pink, violet, and golden, represents it in equal abundance in deeper water.

The genus Sebastopsis differs from Sebastodes only in having no teeth on the palatines. The species, all of small size and red or varied coloration, are confined to the Pacific. Sebastopsis xyris occurs in lower California and Sebastopsis guamensis and S. scaber in Polynesia. Species of this genus are often found dried in Chinese insect boxes.

Helicolenus differs from Sebastiscus only in the total absence of air-bladder. The species are all bright crimson in color, very handsome, and live in deep water. Helicolenus dactylopterus is rather common in the Mediterranean, and is sometimes taken in the Gulf Stream, and also in Japan, where two or three other species occur.

Neosebastes is much like Sebastodes, but the suborbital stay bears strong spines and the dorsal is very high. Neosebastes panda is found in Australia, and N. entaxis in Japan. Setarches is distinguished by the cavernous bones of its head. Species are found in both the Atlantic and Pacific in deep water. Several other peculiar or transitional genera are found in different parts of the Pacific.

In Scorpæna the head is more uneven in outline than in Sebastodes and Sebastichthys, skinny flaps are often present on head and body, the air-bladder is wanting, there are 12 dorsal spines and 24 vertebræ, and on each dorsal spine is a small venom-secreting gland. The species are very numerous, highly varied in color, and found in all warm seas, being known as scorpion-fishes or Rascacios. Two species, Scorpæna scrofa and Scorpæna porcus, are common in the Mediterranean, being regarded as good food-fishes, though disliked by the fishermen.

Of the numerous West Indian species, Scorpæna plumieri, Scorpæna grandicornis, and Scorpæna brasiliensis are best known. Scorpæna guttata is common in southern California and is an excellent food-fish. Scorpæna mystes is found on the west coast of Mexico. Scorpæna onaria and S. izensis are found in Japan. Fossil remains referred to Scorpæna are recorded from the Tertiary rocks.

In the islands of the Pacific are numerous dwarf species less than three inches long, which have been set apart as a separate genus, Sebastapistes. The longest known of these is Sebastapistes strongensis, named from Strong Island, abundant in crevices in the corals throughout Polynesia, and much disliked by fishermen.

The genus Scorpænopsis differs from Scorpæna in the absence of palatine teeth. It is still more fantastic in form and color. Scorpænopsis cirrhosa, Scorpænopsis fimbriata, and other species are widely distributed through the East Indies and Polynesia.

The lion-fishes (Pterois) of the tropical Pacific are remarkable for their long pectoral fins, elongate dorsal spines, and zebra-like coloration. The numerous species are fantastic and handsomely colored, but their poisoned, needle-like spines are dreaded by fishermen. They lurk in crevices in the coral reefs, some of them reaching a foot in length.

Inimicus japonicus, common in Japan, has a depressed and monstrous head and a generally bizarre appearance. It is usually black in color but is largely bright red when found among red algæ. A related species, Inimicus aurantiacus, is blackish when near shore, but lemon-yellow in deep water. (See frontispiece.) A related species in the East Indies is Pelor filamentosum, called Nohu or Gofu in Polynesia.

Still more monstrous are the species of Synanceia, short, thick-set, irregularly formed fishes, in which the poisoned spines reach a high degree of venom. The flesh in all these species is wholesome, and when the dorsal spines are cut off the fishes sell readily in the markets. These fishes lie hidden in cavities of the reefs, being scarcely distinguishable from the rock itself. (See Fig. 168, Vol. I.)

The black Emmydrichthys vulcanus of Tahiti lies in crevices of lava, and could scarcely be distinguished from an irregular lump of lava-rock.

A related form, Erosa erosa, the daruma-okose of Japan, is monstrous in form but often beautifully colored with crimson and gray.

In Congiopus the very strong dorsal spines begin in the head, and the mouth is very small. Dr. Gill makes this genus the type of a distinct family, Congiopodidæ.

Besides these, very many genera and species of small poison-fishes, called okose in Japan, abound in the sandy bays from Tokio to Hindostan and the Red Sea. Some of these are handsomely colored, others are fantastically formed. Paracentropogon rubripinnis and Minous adamsi are the commonest species in Japan. Trachicephalus uranoscopus abounds in the bays of hina. Snyderina yamanokami occurs in Southern Japan.

But few fossil Scorpænidæ are recorded. Scorpænopterus siluridens, a mailed fish from the Vienna Miocene, with a warty head, seems to belong to this group, and Ampheristus toliapicus, with a broad, depressed head, is found in the London Eocene, and various Miocene species have been referred to Scorpæna. Sebastodes rosæ is based on a fragment, probably Pleistocene, from Port Harford, California.

The small family of the Caracanthidæ consists of little fishes of the coral reefs of the Pacific. These are compressed in form, and the skin is rough with small prickles, the head being feebly armed. The species are rare and little known, brown in color with pale spots.

The Skilfishes: Anoplopomidæ.—The small family of skilfishes or Anoplopomidæ consists of two species found on the coast of California and northward. These resemble the Scorpænidæ, having the usual form of nostrils, and the suborbital stay well developed. The skull is, however, free from spines, the scales are small and close-set, and the sleek, dark-colored body has suggested resemblance to the mackerel or hake. Anoplopoma fimbria, known as skilfish, beshow, or coalfish, is rather common from Unalaska to Monterey, reaching a length of two feet or more. In the north it becomes very fat and is much valued as food. About San Francisco it is dry and tasteless.

The Greenlings: Hexagrammidæ.—The curious family of greenlings, Hexagrammidæ, is confined to the two shores of the North Pacific. The species vary much in form, but agree in the unarmed cranium and in the presence of but a single nostril on each side, the posterior opening being reduced to a minute pore. The vertebræ are numerous, the scales small, and the coloration often brilliant. The species are carnivorous and usually valued as food. They live in the kelp and about rocks in California and Japan and along the shores of Siberia and Alaska. The atka-fish (Pleurogrammus monopterygius) is one of the finest of food-fishes. This species reaches a length of eighteen inches. It is yellow in color, banded with black, and the flesh is white and tender, somewhat like that of the Lake whitefish (Coregonus clupeiformis), and is especially fine when salted. This fish is found about the Aleutian Islands, especially the island of Atka, from which it takes its name. It is commercially known as Atka mackerel.

In this genus there are numerous lateral lines, and the dorsal fin is continuous. In Hexagrammos, the principal genus of the family, the dorsal is divided into two fins, and there are about five lateral lines on each side.

Hexagrammos decagrammus is common on the coast of California, where it is known by the incorrect name of rock-trout. It is a well-known food-fish, reaching a length of eighteen inches. The sexes are quite unlike in color, the males anteriorly with blue spots, the females speckled with red or brown.

Hexagrammos octogrammus, the common greenfish of Alaska, and the greenling Hexagrammos stelleri, are also well-known species. Close to the latter species is the Abura ainame, or fat cod, Hexagrammos otakii, common throughout Japan. The red rock-trout, Hexagrammos superciliosus, is beautifully variegated with red, the color being extremely variable. Other species are found in Japan and Kamchatka. Agrammus agrammus of Japan differs in the possession of but one lateral line. Ophiodon elongatus, the blue cod, cultus cod, or Buffalo cod of California, is a large fish of moderate value as food, much resembling a codfish, but with larger mouth and longer teeth. The flesh and bones are deeply tinged with bluish green. Cultus is the Chinook name for worthless. Zaniolepis latipinnis is a singular-looking fish, very rough, dry, and bony, occasionally taken on the California coast. Oxylebius pictus is a small, handsome, and very active little fish, whitish with black bands, common among rocks and algæ on the California coast. It is, however, rarely brought into the markets, as it shows great skill in escaping the nets.

No fossil Hexagrammidæ are known.

The Flatheads or Kochi: Platycephalidæ.—The family of Platycephalidæ consists of spindle-shaped fishes, with flattened, rough heads and the body covered with small, rough scales. About fifty species occur in the East Indian region, where the larger ones are much valued as food. The most abundant species and usually the largest in size is Platycephalus insidiator, the kochi of the Japanese. The genus Insidiator contains smaller species with larger scales. In all these the head is very much depressed, a feature which separates them from all the Scorpænidæ. Hoplichthys langsdorfi, the nezupo or rat-tail of Japan, is the type of a separate family, Hoplichthyidæ, characterized by a bony armature of rough plates. Bembras japonicas, another little Japanese fish, with the ventrals advanced in position and the skin with rough plates, is the type of the family of Bembradidæ.

The Sculpins: Cottidæ.—The great family of Cottidæ or sculpins is one especially characteristic of the northern seas, where a great variety of species is found. These differ in general from the Scorpænidæ, from which they are perhaps derived, in the greater number of vertebræ and in the relative feebleness or degeneration of the spinous dorsal, the ventrals, and the scales. In all these regards great variation exists. In the most primitive genus, Jordania, the body is well scaled, the spinous dorsal well developed, and the ventral rays I, 5. In Hemitripterus a large number of dorsal spines remains, but the structure in other regards is highly modified. In the most degraded types, Cottunculus, Psychrolutes, Gilbertidia, which are also among the most specialized, there is little trace of spinous dorsal, the scales are wholly lost, and the ventral fin is incomplete. Most of the species of Cottidæ live on the bottom in shallow seas. Some are found in deep water and a few swarm in the rivers. All are arctic or subarctic, none being found to the south of Italy, Virginia, California, and Japan. None are valued as food, being coarse and tough. Scarcely any are found fossil.

Of the multitude of genera of Cottidæ we notice a few of the most prominent. Jordania zonope, a pretty little fish of Puget Sound, is the most primitive in its characters, being closely allied to the Hexagrammidæ.

Scorpænichthys marmoratus, the great sculpin, or cabezon, of California reaches a length of 2½ feet. It has the ventral rays I, 5, although almost in all the other sculpins the rays are reduced to I, 3 or I, 4. The flesh has the livid blue color seen in the cultus cod Ophiodon elongatus.

To Icelinus, Artedius, Hemilepidotus, Astrolytes, and related genera belong many species with the body partly scaled. These are characteristic of the North Pacific, in which they drop to a considerable depth. Icelus, Triglops, and Artediellus are found also in the North Atlantic, the Arctic fauna of which is derived almost entirely from Pacific sources. The genus Hemilepidotus contains coarse species, with bands of scales. The "Irish lord," Hemilepidotus jordani, a familiar and fantastic inhabitant of Bering Sea, is much valued by the Aleuts as a food-fish, although the flesh is rather tough and without much flavor. Almost equally common in Bering Sea is the red sculpin, Hemilepidotus hemilepidotus, and the still rougher Ceratocottus diceraus. The stone-sculpin, or buffalo-sculpin, Enophrys bison, with bony plates on the side and rough horns on the preopercle, is found about Puget Sound and southward. In all these large rough species from the North Pacific the preopercle is armed with long spines which are erected when the fish is disturbed. This makes it almost impossible for any larger fish to swallow them.

The genera Cottus and Uranidea include the miller's thumbs, also called in America, blob and muffle-jaws, of the Northern rivers. These little fishes are found in Europe, Asia, and America wherever trout are found. They lurk under weeds and stones, moving with the greatest swiftness when disturbed. They are found in every cold stream of the region north of Virginia, and they vie with the sticklebacks in their destruction of the eggs and fry of salmon and trout. Cottus gobio is the commonest species of Europe. Cottus ictalops is the most abundant of the several species of the eastern United States, and Cottus asper in streams of the Pacific Coast, though very many other species exist in each of these regions. The genus Uranidea is found in America. It is composed of smaller species with fewer teeth and fin-rays, the ventrals I, 3. Uranidea gracilis is the commonest of these, the miller's thumb of New England. Rheopresbe fujiyamæ is a large river sculpin in Japan.

Trachidermus ansatus is another river species, the "mountain-witch" (yamanokami) of Japan, remarkable for a scarlet brand on its cheek, conspicuous in life.

The chief genus of Atlantic sculpins is Myoxocephalus, containing large marine species, in structure much like the species of Cottus. Myoxocephalus bubalis is the European fatherlasher, or proach; the European sculpin is Myoxocephalus scorpius. The very similar daddy sculpin of New England is Myoxocephalus grœnlandicus. This species swarms everywhere from Cape Cod northward.

According to Fabricius, Myoxocephalus grœnlandicus is "abundant in all the bays and inlets of Greenland, but prefers a stony coast clothed with seaweed. It approaches the shore in spring and departs in winter. It is very voracious, preying on everything that comes in its way and pursuing incessantly the smaller fish, not sparing the young of its own species, and devouring crustacea and worms. It is very active and bold, but does not come to the surface unless it be led thither in pursuit of other fish. It spawns in December and January and deposits its red-colored roe on the seaweed. It is easily taken with a bait, and constitutes the daily food of the Greenlanders, who are very fond of it. They eat the roe raw."

The little sculpin, or grubby, of the New England coast is Myoxocephalus æneus, and the larger eighteen-spined sculpin is Myoxocephalus octodecimspinosus. Still more numerous and varied are the sculpins of the North Pacific, Myoxocephalus polyacanthocephalus being the best known and most widely diffused. Oncocottus quadricornis is the long-horned sculpin of the Arctic Europe, entering the lakes of Russia and British America. Triglopsis thompsoni of the depths in our own Great Lakes seems to be a dwarfed and degenerate descendant of Oncocottus.

The genus Zesticelus contains small soft-bodied sculpins from the depths of the North Pacific. Zesticelus profundorum was taken in 664 fathoms off Bogoslof Island and Zesticelus bathybius off Japan. In this genus the body is very soft and the skeleton feeble, the result of deep-sea life. Another deep-water genus less degraded is Cottunculus, from which by gradual loss of fins the still more degraded Psychrolutes (paradoxus) and Gilbertidia (sigolutes) are perhaps descended. In sculpins of this type the liparids, or sea-snails, may have had their origin. Among the remaining genera Gymnocanthus (tricuspis, etc.) has no vomerine teeth. Leptocottus (armatus) and Clinocottus (analis) abound on the coast of California, and Pseudoblennius (percoides) is found everywhere along the shores of Japan. Vellitor centropomus of Japan is remarkable among sculpins for its compressed body and long snout. Dialarchus snyderi of the California rock-pools is perhaps the smallest species of sculpin, Blepsias (cirrhosus), Nautichthys (oculofasciatus), and Hemitripterus (americanus), the sea-raven, among the most fantastic. In the last-named genus the spinous dorsal is many-rayed, as in Scorpænidæ, a fact which has led to its separation by Dr. Gill as a distinct family. But the dorsal spines are equally numerous in Jordania, which stands at the opposite extreme of the cottoid series.

In Ascelichthys (rhodorus), a pretty sculpin of the rock-pools of the Oregon region, the ventral fins are wholly lost. Ereunias grallator, a deep-water sculpin from Japan, without ventrals and with free rays below its pectorals, should perhaps represent a distinct family, Ereuniidæ.

The degeneration of the spinous dorsal in Psychrolutes and Gilbertidia of the North Pacific has been already noticed. These genera seem to lead directly from Cottunculus to Liparis.

Fossil Cottidæ are few. Eocottus veronensis, from the Eocene of Monte Bolca, is completely scaled, with the ventral rays I, 5. It is apparently related to Jordania, but is still more primitive. Lepidocottus (aries and numerous other species, mostly from the Miocene) is covered with scales, but apparently has less than five soft rays in the ventrals. Remains of Oncocottus, Icelus, and Cottus are found in Arctic Pleistocene rocks. The family as a whole is evidently of recent date.

The Rhamphocottidæ consist of a single little sculpin with a large bony and singularly formed head, found on the Pacific Coast from Sitka to Monterey. The species is called Rhamphocottus richardsoni.

The Sea-poachers: Agonidæ.—The sea-poachers or alligator-fishes, Agonidæ, are sculpins inclosed in a coat of mail made by a series of overlying plates, much like those of the sea-horses or the catfishes of the family Loricariidæ. So far as structure goes, these singular fishes are essentially like the Cottidæ, but with a different and more perfect armature. The many species belong chiefly to the North Pacific, a few in the Atlantic and on the coast of Patagonia. Some are found in considerable depth of water. All are too small to have value as food and some have most fantastic forms. Only a few of the most prominent need be noticed. The largest and most peculiar species is Percis japonicus of the Kurile Islands. Still more fantastic is the Japanese Draciscus sachi with sail-like dorsal and anal. Agonus cataphractus, the sea-poacher, is the only European species. Podothecus acipenserinus, the alligator-fish, is the commonest species of the North Pacific. Pallasina barbata is as slender as a pipefish, with a short beard at the chin. Aspidophoroides monopterygius of the Atlantic and other similar species of the Pacific lack the spinous dorsal fin.

No fossil Agonidæ are known.

The Lump-suckers: Cyclopteridæ.—The lump-suckers, Cyclopteridæ, are structurally very similar to the Cottidæ, but of very different habit, the body being clumsy and the movements very slow. The ventral fins are united to form a sucking disk by which these sluggish fishes hold fast to rocks. The skeleton is feebly ossified, the spinous dorsal fin wholly or partly lost, the skin smooth or covered with bony warts. The slender suborbital stay indicates the relation of these fishes with the Cottidæ. The species are chiefly Arctic, the common lumpfish or "cock and hen paddle," Cyclopterus lumpus, abounding on both shores of the North Atlantic. It reaches a length of twenty inches, spawning in eel-grass where the male is left to watch the eggs. Cyclopterichthys ventricosus is a large species with smooth skin from the North Pacific.

The Sea-snails: Liparididæ.—The sea-snails, Liparididæ are closely related to the lumpfishes, but the body is more elongate, tadpole shaped, covered with very lax skin, like the "wrinkled skin on scalded milk." In structure the liparids are still more degenerate than the lumpfishes. Even the characteristic ventral disk is lost in some species (Paraliparis; Amitra) and in numerous others the tail is drawn out into a point (leptocercal), a character almost always a result of degradation. The dorsal spines are wanting or imbedded in the loose skin, and all trace of spines on the head is lost, but the characteristic suborbital stay is well developed. The numerous species are all small, three to twelve inches in length. They live in Arctic waters, often descending to great depths, in which case the body is very soft. One genus, Enantioliparis, is found in the Antarctic. In the principal genus, Liparis, the ventral disk is well developed, and the spinous dorsal obsolete. Liparis liparis is found on both shores of the North Atlantic, and is subject to large variations in color. Liparis agassizi is abundant in Japan and northward, and Liparis pulchellus in California. In the most primitive genus, Neoliparis, a notch in the fin indicates the separation of the spinous dorsal. Neoliparis montagui is common in Europe, replaced in New England by Neoliparis atlanticus. Careproctus, with numerous elongate species, inhabits depths of the North Pacific. In Paraliparis (or Hilgendorfia) ulochir, the ventral disk is gone and the lowest stage of degradation of the Loricate or Scorpæna-Cottus type of fishes is reached. No fossil lump-suckers or liparids are recorded, although remains of Cyclopterus lumpus are found in nodules of glacial clay in Canada.