THE GYMNOTID EELS OF TROPICAL AMERICA. 155 



XV. Sternarchogiton Eigenmann and Ward. 



Sternarchogiton Eigenmann and Ward, Proc. Wash. Acad. Sci., VII, 164, 1905. 



Type, Sternarchus nattereri Steindachner. 



Distinguished by the absence of teeth in the upper jaw, otherwise like Stern- 

 archus. 



A genus of a single species. 



Fig. 16. Sternarchogiton nattereri (Steindachner). 



26. Sternarchogiton nattereri (Steindachner). 



Sternarchus nattereri Steindachner, Die Gymnotidse, 3, pi. II, fig. 1, 1888 (Barra 

 do Rio Negro); GtJNTHER, Cat., VIII, 3, 1870; Eigenmann and Eigenmann, 

 Proc, U. S. Nat. Mus., XIV, 1891, 62; Boulenger, Trans. Zool. Soc, XIV, 

 427, 1898 (Rio Jurua). 



Sternarchogiton nattereri Eigenmann and Ward, Proc. Wash. Acad. Sci., VII, 165, 

 1905 (Barra do Rio Negro; Jurua); von Ihering, Os Peixes do Brazil, Part 

 1 A, 1907; Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 

 448 (Barra do Rio Negro). 

 "Length of the head about 12, depth of the body a little more than 8 in the 



total length; snout 3.5, pectoral 1, the caudal about 2 in the length of the head; 



anal rays 197; the pointed pectoral with 16 rays; the almost completely scaled 



caudal with 18 or 19 rays. Scales of the lateral line and the neighboring ones 



larger than the others. 



"Upper jaw without teeth, those of the lower small and in a single row." 



(After Steindachner.) 



Distribution: Middle and Upper Amazons. 



XVI. Adontosternarchus genus nov. 



Type, Sternarchus sachsi Peters. 



Distinguished from all other Sternarchince by the absence of teeth from both 

 jaws, and by the pecuHar V-shaped groove in lower jaw into which the beaklike 

 upper fits. 



A genus of a single species, A . sachsi. 



