670 FISHES. 



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. (LeptocepJiali, see p. 179.) At 

 Monte Bolca fossil remains are very numerous, belonging to 

 recent genera, Anguilla, Sphagebranchus, and Ophiclithys ; 

 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 {Muroenidce platyschistce) ; in others, 

 the true Mursense, (Murcenidce engyschistw) they are narrow. 



Nemichthys. — Exceedingly elongate, band-shaped ; tail taper- 

 ing 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 upiper part being formed by the 

 vomer and intermaxiUaries. 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 sur- 

 rounding, the tail. Pectoral fins well developed. Eye very 

 small. 



Known from two specimens only, 4J inches long, dredged 

 in depths of 1500 and 1800 fathoms in the Pacific and 

 Antarctic Oceans. 



Saccopharynx. — Deep-sea Congers, with the muscular system 

 very feebly developed, with the bones very thin, soft, and 



