Three species, of which one (S. marmoratus) is extremely common in tropical America, and the other (S. bengalensis) not less so in the East Indies.
Chilobranchus.—Vent in the anterior half of the length of the body, which is naked. Vertical fins reduced to a simple cutaneous fold, without rays.
A small fish (Ch. dorsalis) from North Western Australia and Tasmania.
Thirty-First Family—Murænidæ.
Body elongate, cylindrical or “band-shaped, naked or with rudimentary scales. Vent situated at a great distance from the head. Ventral fins none. Vertical fins, if present, confluent, or separated by the projecting tip of the tail. Sides of the upper jaw formed by the tooth-bearing maxillaries, the fore part by the intermaxillary, which is more or less coalescent with the vomer and ethmoid. Humeral arch not attached to the skull. Stomach with a blind sac; no pyloric appendages. Organs of reproduction without efferent ducts.
The “Eels” are spread over almost all fresh waters and seas of the temperate and tropical zones; some descend to the greatest depths of the oceans. The young of some have a limited pelagic existence. (Leptocephali, see p. 179.) At Monte Bolca fossil remains are very numerous, belonging to recent genera, Anguilla, Sphagebranchus, and Ophichthys; even larval Leptocephales have been preserved. Anguilla has been found also in the chalk of Aix and Oeningen.
In the majority of the species the branchial openings in the pharynx are wide slits (Murænidæ platyschistæ); in others, the true Murænæ, (Murænidæ engyschistæ) they are narrow.
Nemichthys.—Exceedingly elongate, band-shaped; tail tapering into a point. Vent approximate to the pectorals, but the abdominal cavity extending far behind the vent. Jaws produced into a long slender bill, the upper part being formed by the vomer and intermaxillaries. The inner surface of the bill covered with small tooth-like asperities. Eye large. The nostrils of each side are close together, in a hollow before the eye. Gill-openings wide, nearly confluent. Pectoral and vertical fins well developed.
This very singular type is a deep-sea form, occurring at depths of from 500 to 2500 fathoms. The two species known have hitherto been found in the Atlantic only.
Cyema.—This genus combines the form of the snout of Nemichthys, with the soft and shorter body of a Leptocephalus; but the gill-openings are very narrow and close together on the abdominal surface. Vent in about the middle of the length of the body; vertical fins well developed, confined to, and surrounding, the tail. Pectoral fins well developed. Eye very small.