Genera allied to Conger are Poeciloconger, Congromurcæna, Uroconger, and Heteroconger.
Murænesox.—Scaleless. Snout produced. Jaws with several series of small closely set teeth, anteriorly with canines; vomer with several long series of teeth, the middle of which is formed by large conical or compressed teeth. Gill-openings wide, approximate to the abdomen. Pectoral and vertical fins well developed, the dorsal beginning above the gill-opening. Two pairs of nostrils, the posterior opposite to the upper part or middle of the eye.
Four species from tropical seas, M. cinereus being very common in the Indian Ocean, and attaining to a length of six feet.
Nettastoma.—Scaleless. Snout much produced, depressed. Jaws and vomer with bands of card-like teeth, those along the median line of the vomer being somewhat the larger. Vertical fins well developed; pectorals none. Gill-openings of moderate width, open. Nostrils on the upper surface of the head, valvular; the anterior near to the end of the snout, the posterior above the anterior angle of the eye.
This genus lives at some depth, the Japanese species (N. parviceps) having been obtained at 345 fathoms. N. melanurum from the Mediterranean, seems to inhabit a similar depth. Hyoprorus is its Leptocephalid form.
Genera allied to Murcænesox are Saurenchelys, Oxyconger, Hoplunnis, and Neoconger; in all these the nostrils have a superior or lateral position. In other genera the nostrils perforate the upper lip, as in Myrus, Myrophis, Paramyrus, Chilorhinus, Murænichthys, and Ophichthys, the last genus deserving of particular mention on account of its great range and common occurrence.
Ophichthys.—Nostrils labial; extremity of the tail free, not surrounded by a fin.
More than eighty species are known, many of which are abundant on the coasts of the tropical and sub-tropical zones. They do not attain to a large size, but many must be extremely voracious and destructive to other fishes, if we draw an inference from the formidable dentition with which their jaws and palate is armed. Other species have much more feeble, and some even obtuse teeth, better adapted for seizing Crustaceans than vigorous and slippery fishes. Some have rudimentary pectoral fins or lack them altogether. Many are highly ornamented with bands or spots, the coloration being apparently very constant in the several species.
Fig. 303.—Ophichthys crocodilinus, from the Indo-Pacific.