Fig. 209.—Lophius piscatorius.
Fig. 210.—A young Fishing-Frog.
The habits of all these species are identical. The wide mouth extends all round the anterior circumference of the head, and both jaws are armed with bands of long pointed teeth, which are inclined inwards, and can be depressed so as to offer no impediment to an object gliding towards the stomach, but prevent its escape from the mouth. The pectoral and ventral fins are so articulated as to perform the functions of teeth, the fish being enabled to move, or rather to walk, on the bottom of the sea, where it generally hides itself in the sand, or amongst seaweed. All round its head, and also along the body, the skin bears fringed appendages, resembling short fronds of seaweed; a structure which, combined with the extraordinary faculty of assimilating the colours of the body to its surroundings, assists this fish greatly in concealing itself in places which it selects on account of the abundance of prey. To render the organisation of these creatures perfect in relation to their wants, they are provided with three long filaments inserted along the middle of the head, which are, in fact, the detached and modified three first spines of the anterior dorsal fin. The filaments most important in the economy of the fishing-frogs is the first, which is the longest, terminates in a lappet, and is movable in every direction. There is no doubt that the Fishing-frog, like many other fish provided with similar appendages, plays with this filament as with a bait, attracting fishes, which, when sufficiently near, are ingulfed by the simple act of the Fishing-frog opening its gape. Its stomach is distensible in an extraordinary degree, and not rarely fishes have been taken out of it quite as large and heavy as their destroyer. The British species grows to a length of more than five feet; specimens of three feet are common. Baird records that the spawn of the same species has been observed as a floating sheet of mucus, of from some 60 to 100 square feet.
Ceratias.—Head and body much compressed and elevated; cleft of the mouth wide, subvertical. Eyes very small. Teeth in the jaws rasp-like, depressible; palate toothless. Skin covered with numerous prickles. The spinous dorsal is reduced to two long isolated spines, the first on the middle of the head, the second on the back. The soft dorsal and anal short; caudal very long. Ventrals none; pectorals very short. Two and a half gills. Skeleton soft and fibrous.
Ceratias holbölli, a deep-sea fish; only a few examples have been found near the coast of Greenland, and from the mid-Atlantic; the latter at a depth of 2400 fathoms. Deep black.
Himantolophus.—Head and body compressed and elevated; cleft of the mouth wide, oblique. Eyes very small. Teeth of the jaws rasp-like, depressible; palate toothless. Skin with scattered conical tubercles. The spinous dorsal is reduced to a single tentacle on the head. The soft dorsal, anal, caudal, and pectoral short. Ventrals none. Three and a half gills. Skeleton soft and fibrous.
This is another deep-sea form, hitherto found in very few examples in the Arctic and Mid-Atlantic Oceans. The single tentacle is beset with many long filaments at its extremity, thus answering the same purpose which is attained by a greater number of tentacles. Deep black.
Melanocetus.—Head and body compressed; head very large; cleft of the mouth exceedingly wide, vertical. Eyes very small. Teeth of the jaws and vomer rasp-like, depressible. Skin smooth. The spinous dorsal is reduced to a single filament placed on the head. The soft dorsal and anal short. Ventrals none.
