The Angler-fishes.—The few remaining fishes possess also jugular ventral fins, but in other regards they show so many peculiarities of structure that we may well consider them as forming a distinct order, Pediculati (pedicula, a foot-stalk), although the relation of these forms to the Batrachoididæ seems a very close one.

The most salient character of the group is the reduction and backward insertion of the gill-opening, which is behind the pectoral fins, not in front of them as in all other fishes. The hypocoracoid and hypercoracoid are much elongate and greatly changed in form, so that the pectoral fin is borne on the end of a sort of arm. The large ventrals are similarly more or less exserted. The spinous dorsal is much reduced, the first spine being modified to form a so-called fishing-rod, projecting over the mouth with a fleshy pad, lure, or bait at its tip. The form of the body varies much in the different families. The scales are lost or changed to prickles and the whole aspect is very singular, and in many cases distinctly frog-like. The species are mostly tropical, some living in tide-pools and about coral reefs, some on sandy shores, others in the oceanic abysses.

The nearest allies of the Pediculates among normal fishes are probably the Batrachoididæ. One species of Lophiidæ is recorded among the fossils, Lophius brachysomus, from the Eocene of Monte Bolca. No fossil Antennariidæ are known. Fossil teeth from the Cretaceous of Patagonia are doubtfully named "Lophius patagonicus."

The Fishing-frogs: Lophiidæ.—In the most generalized family, that of the fishing-frogs (Lophiidæ), the body is very much depressed, the head the largest part of it. The mouth is excessively wide, with strong jaw-muscles, and strong sharp teeth. The skin is smooth, with dermal flaps about the head. Over the mouth, like a fishing-rod, hangs the first dorsal spine with a lure at the tip. The fishes lie flat on the bottom with sluggish movements except for the convulsive snap of the jaws. It has been denied that the bait serves to attract small fishes to their destruction, but the current belief that it does so is certainly plausible. As to this Dr. Gill observes:

"The name 'angler' is derived from the supposition that by means of the foremost dorsal spine, which bears leaf-like tags, or appendages, at the end, it angles for fishes itself, lying upon the ground with its head somewhat upraised. According to Mr. S. Kent, however, this is at most only partly the case: 'That the fish deliberately uses this structure as a fisherman does his rod and line for the alluring and capture of other fish is a matter of tradition handed down to us from the time of Pliny and Aristotle, and which scarcely any authority since their time has ventured to gainsay. Nevertheless, like many of the delightful natural-history romances bequeathed to us by the ancient philosophers, this one of the angler-fish will have to be relegated to the limbo of disproved fiction. The plain and certain ground of facts, all the same, has frequently more startling revelations in store for us than the most fervid imaginations of philosophers, and that this assertion holds good in the case now under consideration must undoubtedly be admitted. It is here proposed to show, in fact, that the angler is one of the most interesting examples upon which Nature has exercised her handicraft, in the direction of concealing the identity of her protégé, such ingenuity being sometimes utilized with the object of protecting the organism from the attacks of other animals, or, as illustrated in the present instance, for the purpose of enabling it by stealth to obtain prey which it lacks the agility to hunt down after the manner of ordinary carnivorous fishes. To recognize the several details here described, it will not suffice to refer to examples simply, and usually most atrociously stuffed, nor even to those preserved in spirit, in which all the life colors are more or less completely obliterated and the various membranous appendages shrunk up and distorted. In place of this, a healthy, living example fresh from the sea, or, better still, acclimatized in the tanks of an aquarium, must be attentively examined, and whereupon it will be found that this singular fish, throughout the whole extent of its superficies, may be appropriately designated a living sham."

It was, in the first place, observed by Mr. Kent "that the fish while quietly reclining upon the bottom of its tank presented a most astonishing resemblance to a piece of inert rock, the rugose prominences in the neighborhood of the head lending additional strength to this likeness. This resemblance being recognized, it was next found, on a little closer inspection, that the fish constituted, in connection with its color, ornamentations, and manifold organs and appendages, the most perfect facsimile of a submerged rock, with that natural clothing of sedentary animal and vegetable growths common to boulders lying beneath the water in what is known as the laminarian zone. In this manner the numerous simple or lobulated membranous structures dependent from the lower jaw and developed as a fringe along the lateral line of the body imitate with great fidelity the little flat calcareous sponges (Grantia), small compound ascidians, and other low organized zoophytic growths that hang in profusion from favorably situated submarine stones. That famous structure known as the angler's 'rod and bait' finds its precise counterpart in the early growing phase of certain sea-plants, such as the oarweed (Laminaria), while the more posterior dorsal fin-rays, having short lateral branchlets, counterfeit in a like manner the plant-like hydroid zoophytes known as Sertulariæ. One of the most extraordinary mimetic adaptations was, however, found in connection with the eyes, structures which, however perfectly the surrounding details may be concealed, serve, as a rule, to betray the animal's presence to a close observer. In the case of the angler, the eyes during life are raised on conical elevations the sides of which are separated by darker longitudinal stripes into symmetrical regions, the structure, as a whole, with its truncated summit upon which the pupil opens, reproducing with the most wonderful minuteness the multivalve shell of a rook barnacle (Balanus). To complete the simile the entire exposed surface of the body of the fish is mapped out by darker punctated lines into irregular polygonal areas, whose pattern is at once recognized by the student of marine zoology as corresponding with that of the flat, cushion-like expansions of the compound tunicate Botryllus violaceus. Thus disguised at every point, the angler has merely to lie prone, as is its wont, among the stones and débris at the bottom of the sea and to wait for the advent of its unsuspecting prey, which, approaching to browse from what it takes to be a flat rock—differing in no respect from that off which it obtained the last appetizing morsel of weed or worm—finds itself suddenly engulfed beyond recall within the merciless jaws of this marine impostor."

The great fishing-frog of the North Atlantic, Lophius piscatorius, is also known as angler, monkfish, goosefish, allmouth, wide-gape, kettleman, and bellows-fish. It is common in shallow water both in America and Europe, ranging southward to Cape Hatteras and to the Mediterranean. It reaches a length of three feet or more. A fisherman told Mr. Goode that "he once saw a struggle in the water, and found that a goosefish had swallowed the head and neck of a large loon, which had pulled it to the surface and was trying to escape. There is authentic record of seven wild ducks having been taken from the stomach of one of them. Slyly approaching from below, they seize birds as they float upon the surface."

"The angler, or goosefish, spawns in summer along the eastern Atlantic coast, and the result of its labor is quite remarkable. 'The eggs are very numerous, inclosed in a ribbon-shaped gelatinous mass, about a foot in width and thirty or forty feet long, which floats near the surface. One of these ribbons will weigh perhaps forty pounds, and is usually partially folded together and visible a foot or eighteen inches from the top of the water, its color being brownish purple. The number of eggs in one of these has been estimated to be from forty to fifty thousand.' The growth of the young after exclusion from the egg is rather rapid, and Professor Goode saw 'young fish two or three inches long' while others were yet spawning, and these young fish were presumably the fry of those that had spawned the same year, only somewhat earlier. In a few days after hatching they present a striking appearance on account of the enormous development of the pectoral and ventral fins."

Aristotle gives, according to Professor Horace A. Hoffman, this account of the angler: "'Inasmuch as the flat, front part is not fleshy, nature has compensated for this by adding to the rear and the tail as much fleshy substance as has been subtracted from the front.' The βάτραχος is called the angler. He fishes with the hair-like filaments hung before his eyes. On the end of each filament is a little knob, just as if it had been placed there for a bait. He makes a disturbance in sandy or muddy places, hides himself and raises these filaments. When the little fish strikes at them he leads them down with the filaments until he brings them to his mouth. The βάτραχος is one of the σελάχη. All the σελάχη are viviparous or ovoviviparous except the βάτραχος. The other flat σελάχη have their gills uncovered and underneath them, but the βάτραχος has its gills on the side and covered with skinny opercula, not with horny opercula like the fish which are not σελαχώδη. Some fishes have the gall-bladder upon the liver, others have it upon the intestine, more or less remote from the liver and attached to it by a duct. Such are βάτραχος, ἔλλοψ, συνάγρίς, σμύραινα, and ξιφίας. The βάτραχος is the only one of the σελάχη which is oviparous. This is on account of the nature of its body, for it has a head many times as large as the rest of its body, and spiny and very rough. For this same reason it does not afterwards admit its young into itself. The size and roughness of the head prevent them both from coming out (i.e., being born alive) and from going in (being taken into the mouth of the parent). The βάτραχος is the most prolific of the σελάχη, but it is scarce because the eggs are easily destroyed, for it lays them in a bunch near the shore."

The genus Lophius of northern range has a vertebral column of about thirty vertebræ. Lophius litulon occurs in Japan. In the North Pacific is found Lophiomus, similar in appearance but smaller in size, ranging southward to the equator, a southern fish having but eighteen vertebræ. Lophiomus setigerus is the common anko of Japan, and other species are recorded from Hawaii, and the Galapagos.

The Sea-devils: Ceratiidæ.—The sea-devils, or Ceratiidæ, are degenerate anglers of various forms, found in the depths of the arctic seas. The body is compressed, the mouth vertical; the substance is very soft, and the color uniform black. Dr. Günther thus speaks of them:

"The bathybial sea-devils are degraded forms of Lophius; they descend to the greatest depths of the ocean. Their bones are of an extremely light and thin texture, and frequently other parts of their organization, their integuments, muscles, and intestines are equally loose in texture when the specimens are brought to the surface. In their habits they probably do not differ in any degree from their surface representative, Lophius. The number of the dorsal spines is always reduced, and at the end of the series of these species only one spine remains, with a simple, very small lamella at the extremity (Melanocetus johnsonii, Melanocetus murrayi). In other forms sometimes a second cephalic spine, sometimes a spine on the back of the trunk, is preserved. The first cephalic spine always retains the original function of a lure for other marine creatures, but to render it more effective a special luminous organ is sometimes developed in connection with the filaments with which its extremity is provided (Ceratias bispinosus, Oneirodes eschrichtii). So far as known at present these complicated tentacles attain to the highest degree of development in Himantolophus and Ægæonichthys. In other species very peculiar dermal appendages are developed, either accompanying the spine on the back or replacing it. They may be paired or form a group of three, are pear-shaped, covered with common skin, and perforated at the top, a delicate tentacle sometimes issuing from the foramen."

Of the fifteen or twenty species of Ceratiidæ described, none are common and all are rare catches of the deep-sea dredge. Caulophryne jordani is remarkable for its large fins and the luminous filaments, Linophryne lucifer for its large head, and Corynolophus reinhardti (Fig. 143, Vol. I) for its luminous fishing-bulb.

The Frogfishes: Antennariidæ.—The frogfishes, Antennariidæ, belong to the tropical seas and rarely descend far below the surface. Most of them abound about sand-banks or coral reefs, especially along the shores of the East and West Indies, where they creep along the rocks like toads. Some are pelagic, drifting about in floating masses of seaweed. All are fantastic in form and color, usually closely imitating the objects about them. The body is compressed, the mouth nearly vertical, and the skin either prickly or provided with fleshy slips.

The species of Pterophryne live in the open sea, drifting with the currents in masses of sargassum. Two species, Pterophryne tumida and Pterophryne gibba, are found in the West Indies and Gulf Stream. Two others very similar, Pterophryne histrio and Pterophryne ranina, live in the East Indies and drift in the Kuro Shiwo of Japan. All these are light olive-brown with fantastic black markings.

The genus Antennarius contains species of the shoals and reefs, with markings which correspond to the colors of the rocks. These fishes are firm in texture with a velvety skin, and the prevailing color is brown and red. There are many species wherever reefs are found. Antennarius ocellatus, the pescador, is the commonest West Indian species. Antennarius multiocellatus, with many ocellated spots, is the Martin Pescador of Cuba, also common.

On the Pacific coast of Mexico the commonest species is Antennarius strigatus. In Japan, Antennarius tridens abounds everywhere on the muddy bottoms of the bays. Antennarius nox is a jet-black species of the Japanese reefs, and Antennarius sanguifluus is spotted with blood-red in imitation of coralline patches. Many other species abound in the East Indies and in Polynesia. The genus Chaunax is represented by several deep-water species of the West Indies, Japan, etc.

The Gigactinidæ of the deep seas differ from the Ogcocephalidæ, according to Boulenger, in the absence of ventrals.

The Batfishes: Ogcocephalidæ.—The batfishes, Ogcocephalidæ, are anglers with the body depressed and covered with hard bony warts. The mouth is small and the bony bases of the pectoral and ventral fins are longer than in any other of the anglers. The species live in the warm seas, some in very shallow water, others descending to great depths, the deep-sea forms being small and more or less degenerate. These walk along like toads on the sea-bottoms; the ventrals, being jugular, act as fore legs and the pectorals extend behind them as hind legs.

The common sea-bat, or diablo, of the West Indies, Ogcocephalus vespertilio, is dusky in color with the belly coppery red. It reaches the length of a foot. The angling spine is very short, hidden under the long stiff process of the snout. Farther north occurs the short-nosed batfish, Ogcocephalus radiatus, very similar, but with the nostril process, or snout, blunt and short. Zalieutes elater, with a large black eye-like spot on each side of the back, is found on the west coast of Mexico. In deeper water are species of Halieutichthys in the West Indies and of Halieutæa in Japan. Dibranchus atlanticus has the gills reduced to two pairs. Malthopsis consists of small species, with the rostrum prominent, like a bishop's miter. Two species are found in the Pacific, Malthopsis mitrata in Hawaii and Malthopsis tiarella in Japan.

And with these dainty freaks of the sea, the results of centuries on centuries of specialization, degeneration, and adaptation, we close the long roll-call of the fishes, living and dead. And in their long genealogy is enfolded the genealogy of men and beasts and birds and reptiles and of all other back-boned animals of whom the fish-like forms are at once the ancestors, the cousins, and the younger brothers. When the fishes of the Devonian age came out upon the land, the potentiality of the higher methods of life first became manifest. With the new conditions, more varied and more exacting, higher and more varied specialization was demanded, and, in response to these new conditions, from a fish-like stock have arisen all the birds and beasts and men that have dwelt upon the earth.