THE GYMNOTID EELS OF TEOPICAL AMERICA. 121 



III. Sternopygus Mtiller and Troschel. 



Gymnotus (in part) Linn^us, Syst. Nat., ed. XII, i, 427, 1766. 

 Sternopygus Muller and Troschel, Horse IchthyoL, III, 13, 1849. 



Type, Gymnotus macrurus Bloch and Schneider. 



Readily distinguished from all the other Gymnotids by the free orbital margin. 

 A frontal fontanel, a caudal filament, no caudal; snout short; head large, gape 

 moderate, curved downward and back; jaws equal, or nearly so, upper overhanging 

 on the sides; teeth minute, conical, in two patches more or less confluent (becoming 

 a single patch in older individuals) on the upper jaw, and a single large patch on 

 lower jaw; air-bladder long and conical. Size moderate to rather large; body 

 compressed; maximum depth in the region of the pectorals. Scales cycloid, 

 rather small; lateral line complete, following axis of the body. Origin of the anal 

 in the pectoral region; caudal peduncle moderately long. 



. Fig. 3. Sternopygus macrurus (Bloch and Schneider). 



Species of Sternopygus. 



a. Snout pointed, upper profile nearly straight; anal not exceeding three hundred rays macrurus. 



aa. Snout very blunt, upper profile distinctly convex; anal having more than three hundred rays. 



obtusirostris. 



3. Sternopygus macrurus (Bloch and Schneider). 



Gymnotus macrurus Bloch and Schneider, 522, 1801. 



Sternopygus macrurus MUller and Troschel, Horse IchthyoL, III, 14, 1849; KauP; 

 Apod., 137, 1856; Steindachner, Die Gymnotidse, ii, 1868 (Surinam; Rio 

 Branco; Borba; Cai^ara); Cope, Proc. Acad. Nat. Sci. Phila., 1871, 257, 

 1872 (Ambyiacu); id., Proc. Am. Philos. Soc, 1878, 57 (Peruvian Amazon); 

 EiGENMANN, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 450 (Orinoco, 

 south to Paraguay ; Rio das Velhas) . 



Sternopygus carapus GIjnther, Cat., VIII, 7, 1870; Lijtken, Velhas Flodens 



