350 MEMOIRS OF THE CARNEGIE MUSEUM 



ventrals; highest dorsal ray 4.5 in the length; adipose fin behind the vertical from 

 the base of the last anal ray ; caudal forked, the longest rays a little greater than the 

 depth; anal slightly emarginate; ventrals reaching anal, pectorals to ventrals, or 

 but a trifle shorter. 



Hyaline; a conspicuous silvery lateral band; sides of head silvery; a vertical 

 humeral spot crossing the second scale of the lateral line; three parallel dark lines 

 along the middle of the back; scales of the back margined with several rows of 

 chromatophores; chromatophores along base of anal and scattering ones on the 

 sides, a band of chromatophores below the silvery band ; a narrow dark band from 

 the tip of the first (short) dorsal ray to the tip of the penultimate, tips of the longer 

 raj r s and bases of all the rays hyaline; caudal everywhere punctate, except at the 

 tips of the rays and a triangular patch adjoining the middle rays above and below, 

 these parts hyaline; tips of highest anal rays milky; tips of the other rays dark, 

 the dark color continued across the longest rays at the same level; pectorals and 

 ventrals more or less dotted. 



210. Astyanax Baird and Girard. 



Astyanax Baird and Girard, Proc. Acad. Nat. Sci. Phila., 1854, 26. 



Type, Astyanax argentatus Baird and Girard. 



Small Tetragonopterids with two series of teeth in the premaxillary, five or 

 more teeth in the inner series; a single series in the mandible, those on the sides 

 being abruptly smaller; a few teeth on the maxillary; lateral line complete, but little 

 decurved; caudal naked, predorsal line scaled; anal short or moderate, its origin 

 behind that of the dorsal; preventral area with normal scales; second suborbital 

 leaving a narrow naked area. 



Key to the Guiana Species of Astyanax. 

 a. Caudal spot minute or none. 



6. A. 25-27 ; scales 34 or 35 guianensis. 



bb. A. 20-22 ; scales 33-35 essequibensis. 



na. A large caudal spot. 



c. A vertical humeral spot; a definite, oval caudal spot. A. 21-24; lateral line 33-35 mutator. 



cc. A large, definite, horizontal, parabolic humeral spot; a diffuse caudal spot; A. 25-26; lateral line 34-35; 



depth 2.3-2.6 mucronatus. 



cce. A large, horizontal humeral spot; depth 3 wappi. 



211. Astyanax guianensis Eigenmann. (Plate LI, fig. 1.) 



Astyanax guianensis Eigenmann, Ann. Carnegie Mus., VI, 1909, 10; Repts. 

 Princeton Univ. Exp. Patagonia, III, 1910, 434. 



