1906.] NATURAL SCIENCES OF PHILADELPHIA. 351 



inserted nearly midway between tip of snout and tip of last anal ray, 

 or well before dorsal, and reaching about f of space to anal. Vent close 

 in front of anal. 



Color in alcohol brown, especially back, sides and lower surface 

 silvered and pale. A humeral blotch. A faint trace of a slightly 

 lighter silvered band from shoulder to base of caudal, posteriorly 

 becoming plumbeous though only slightly dusky at base of caudal, 

 and same shade also continued out on median caudal rays to their tips. 

 Base of each caudal lobe with a pale straw-colored blotch about size 

 of pupil, then membranes between rays blackish and fading out into 

 pale dusky posteriorly. Dorsal brownish with an indistinct dusky 

 cross-streak. Other fins all pale and unmarked. Iris brownish. 



Length 2|- inches. 



Type, No. 21,828, A. N. S. P. Near Santa Anna da Chapada, in 

 Matto Grosso, Brazil, from the headwaters of the Paraguay. August, 

 1884. H. H. Smith. Prof. E. D. Cope. Also paratype. No. 21,829, 

 A. N. S. P., with same data. 



This species is closely related to Astyanax tnoenkhausii (Eigemnann 

 and Kennedy), from which it differs chiefly in the coloration. A. 

 paucidens (Ulrey) and A. jenynsii (Steindachner) both differ in the 

 fewer scales, apparently not more than 33. 



(Named for Santa Anna da Chapada, province of Matto Grosso, 

 Brazil.) 



