THE AMERICAN TETRAGONOPTERINAE. 89 



anal, their distance from tip of snout slightly less than that of the dorsal; high- 

 est dorsal ray three and one half in the length, equal to the caudal lobes; anal 

 but slightly emarginate, its highest ray reaching about to the base of the six- 

 teenth ray, its base about one third of the length ; ventrals not reaching to anal, 

 and the pectorals not quite to the ventrals. 



A faint vertical humeral spot; tips of caudal lobes and middle rays faintly 

 dusky; a well-defined, silvery lateral band, two thirds as wide as the eye; sides 

 iridescent silvery. 



14. Moenkhausia xinguensis (Steindachner) . 



Tetragonopterus xinguensis Steindachner, Flussf. Siidamer., 1882, 4, p. 32 (Xingu); Eigenmann & 



Eigenmann, Proc. U. S. N. M., 1891, 14, p. 53; Ulret, Ann. N. Y. acad. sci., 1895, 8, p. 281. 

 Moenkhausia xingue?isis Eigenmann, Rept. Princeton univ. exped. Patagonia, 1910, 3, p. 438. 



This species is known only from the types. 



"Head 3.33; depth 2.33; D. 11; A. 26; scales 5-32-4; interorbital 3 in the 

 head, snout 3.6. 



Dorsal profile a little more arched than ventral; interorbital nearly flat; 

 maxillary narrow, reaching nearly to the vertical from the middle of the eye. 

 Height of dorsal equals length of head; pectoral equals length of head without 

 the snout, reaching ventrals; ventrals shorter than pectorals, reaching to anal; 

 caudal slightly longer than head. Golden brown, lower parts of head silvery; 

 humeral spot large, ill defined. No caudal spot. Differs from lepidurus in 

 having fewer scales in the lateral line and in the greater depth." Steindachner. 



15. Moenkhausia browni Eigenmann. 



Conia of the Wacusi Indians. 



Plate 12, fig. 2. 



Moenkhausia browni Eigenmann, Ann. Carnegie mus., 1909, 6, p. 13 (Aruataima Falls, Potaro River); 

 Rept. Princeton univ. exped. Patagonia, 1910, 3, p. 438; Mem. Carnegie mus., 1912, 6, p. 324, pi. 

 47, fig. 3. 



Habitat. — Potaro River both above and below the Kaieteur Fall. 



