45° 
TUBEBLADDERED GROUP. 
anal fins are rudimental. As in the last genus, the stomach is capable of great 
distention, and specimens which had swallowed fish of many times their own 
weight have been found floating in the Atlantic with this organ dilated to its 
utmost. In a third type (Nemichthys), from depths between five hundred and two 
thousand fathoms in the Atlantic, the exceedingly elongate body is band-shaped, 
with the tail tapering to a point, and the jaws produced into a long slender beak. 
It has been already noticed that in one of the deep-sea eels the 
gill-openings are confluent into a longitudinal slit on the under 
surface of the body ; and a very similar condition characterises the second family 
(Symbranchidce) of eels, only in this case the slit is transverse. A better dis¬ 
tinction is, however, afforded by the structure of the upper jaw, the margin of 
which in the present family is formed entirely by the premaxillse, on the inner 
side of which lie the maxillse. The paired fins are rudimental, and the vertical 
Single-Slit Eels. 
BENGAL SHORT-TAILED EEL (i nat. Size). 
ones wanting; while the scales, if present, are minute ; and accessory breathing- 
organs may be developed. An air-bladder is wanting, the stomach has no blind 
appendage, and the ovaries are furnished with ducts ; the vent being situated far 
behind the head. Whereas the majority of these eels inhabit fresh and brackish 
waters in tropical Asia and America, they are also represented in Australia, where 
one genus is marine. Of the fresh-water forms, the most remarkable is the 
amphibious eel (Amphipnous cuchia ) of Bengal, in which there is an accessory 
breathing-apparatus, the body is scaled, and the pectoral girdle is detached from the 
skull. There are only three gill-arches with rudimentary laminae, separated from 
one another by narrow slits; and the additional breatliing-organ takes the form of 
a lung-like sac on each side of the neck communicating with the gill-chamber. 
Day states that “ this amphibious fish, when kept in an aquarium, may be 
observed constantly rising to the surface for the purpose of respiring atmospheric 
air direct. It usually remains with the snout close to the surface, and in like 
manner lies in the grassy sides of ponds and stagnant pieces of water, so that 
