142 



NATURAL HISTORY. 



The type of the seventh group is the genus Myi-us, in which the nostrils are upon the margin of 

 the upper lip. and the tongue is fixed as in the preceding group. 



In the genus Mursenichthys the body is long and worm-like, and without pectoral fins. The 

 species frequent the Indian Archipelago. 



The eighth group chiefly comprises the species of the genus Ophichthys, which are very numerous. 

 The nostrils are placed as in the last group, but the extremity of the tail is not surrounded by tins. 

 In some of the species, such as Ophichthys quadratus, from China, the tail is four-sided, and the dorsal 

 and anal fins are absent. The pectoral fins present all degrees of development ; the teeth, too, are very 

 variable, and in some species, like Ophichthys boro, they are granular. This species occurs in both the 



CONGEK EEL. 



fresh waters and seas of the East Indies, and apparently has been met with in the West Indies also. 

 Other species have the lips fringed. 



The ninth group comprises the genus Moringua. It has the tail much shorter than the trunk, and 

 the heart situated far behind the gills, and as in so many of the Eels the gill-openings are narrow and 

 on the under side. The species occur in the East Indian Islands, but range to Japan. There are 

 about ninety vertebrae in the body and forty in the tail. 



The tenth group has the genus Mursena for its type. It contains a very large number of species, 

 which are all without scales and have no pectoral fins. The teeth vary a good deal with age, as the 

 series are more numerous in the young than in the adult. In a good many forms the teeth are sharp, 

 in others, feeding on Crustacea, they are blunt and have the character of grinders. Some species have 

 the posterior nostrils tubular. The ornamentation may consist of spots, which are brown or black, 

 round or polygonal. Sometimes there ai-e black cross-bands, while other species are ornamented 

 with a network of yellowish lines. The Murtena macrurus, which reaches a length of fully ten feet, 

 has the tail twice as long as the body. The Mursena richardsonii, another Indian type, has the skin 

 folded, with the folds crossing each other so as to form pouches. The Muraena undulata is incapable 

 of completely slmtting its mouth. 



