Body covered with thin, deciduous scales; barbels none. Margin of the upper jaw formed by the intermaxillaries mesially, and by the maxillaries laterally, both bones being firmly united, in juxtaposition. Opercular apparatus complete. Adipose fin none; the dorsal fin belongs to the caudal portion of the vertebral column. Stomach with a blind sac; intestine short, the mucous membrane forming a spiral fold; pyloric appendages none. Pseudobranchiæ none; air-bladder incompletely divided into cells; gill-opening wide.
One genus and species only (Chirocentrus dorab) is known, which is common in the Indian Ocean, and attains to a length of about three feet; it is not esteemed as food. Remains of fishes similar to Chirocentrus are found in the marl slates of Padang, in Sumatra.
Twenty-fifth Family—Alepocephalidæ.
Body with or without scales; head naked; barbels none. Margin of the upper jaw formed by the intermaxillaries and maxillaries, the former being placed along the upper anterior edge of the latter. Opercular apparatus complete. Adipose fin none; the dorsal fin belongs to the caudal portion of the vertebral column. Stomach curved, without blind sac; pyloric appendages in moderate number. Pseudobranchiæ; air-bladder absent. Gill-openings very wide.
Before the voyage of the “Challenger” one species only of this family was known, Alepocephalus rostratus, a rare fish from the Mediterranean; now, four genera with seven species are known, and there is no doubt that this family is one of the most characteristic, and will prove to be one of the most generally distributed forms, of the deep-sea. Their vertical range varies between 345 (Xenodermichthys) and 2150 (Bathytroctes) fathoms. They approach the Salmonoids, but lack invariably the adipose fin. Their dentition is very feeble; their eye large; bones thin. Coloration black.
Alepocephalus has thin cycloid scales; a mouth of moderate width, and no teeth on the maxillary.
Bathytroctes has cycloid scales, a wide mouth, and teeth on the maxillary as well as intermaxillary.
Platytroctes has small keeled scales and no ventrals.
Xenodermichthys with fine nodules instead of scales.