EEL TRIBE. 



45 1 



without trouble it may obtain access to air." Indeed, the chief respiration of 

 this fish is carried on by means of the two sacs on the sides of the neck, which 

 can be inflated and emptied at will. In the other two fresh- water genera, one of 

 which (Monopterus) is confined to the Oriental region, while the other (Symbran- 

 chus) has a distribution coextensive with that of the family, there is no additional 

 breathing-organ, the body is naked, and the pectoral girdle is attached to the 

 .skull. Whereas in the former of these genera the gills are rudimental, in the 

 latter they are well developed ; and, in the absence of an accessory apparatus, it 

 .seems strange how the one species with rudimental gills manages to breath at 

 all. The Bengal short-tailed eel (Symbranchus bengalensis) has been selected to 

 illustrate the external form of the members of this very remarkable family. 



Electric Eel. 



ELECTRIC EEL ( J nat. size). 



Together with four other genera from the fresh waters of Tropical 

 America, the well-known electric eel (Gymnotus electricus) constitutes 

 the third and last family of the group under consideration, the leading charac- 

 teristics of which are as follows. The jaws are formed in the same manner as in 

 the true eels, and the head is scaleless and without barbels. The dorsal fin is 

 either totally wanting, or reduced to a fatty rudiment; the anal is extremely 

 elongated ; pelvics are wanting : and the caudal is likewise generally absent, the 

 tail terminating in a point, which, when broken off, can be renewed in the same 

 manner as in the blind- worms. The vent is situated in or near the throat ; the 

 gill-openings are rather narrow; an air-bladder is present; the stomach has a 

 blind appendage; and the ovaries are provided with ducts. In the skeleton the 

 pectoral girdle is attached to the skull. By Professor Cope the typical genus is 

 considered to be to a certain extent intermediate between the last family and the 

 eel-like representatives of the cat-fishes. 



