266 



THE AMERICAN CHARACIDAE. 



third suborbitals leaving a narrow naked margin behind and below. Maxil- 

 lary as long as the eye, shorter than the mandible, which is equal to the snout and 

 half the length of the eye. Premaxillary with four broadly tricuspid teeth in 

 the outer row and five brown-tipped 4- to 5-pointed teeth in the inner row. 

 Maxillary with a single minute tooth in the upper angle. Mandible with five 

 sharp 3- to 4-pointed teeth. 



Origin of dorsal about equidistant from the snout and the base of the 

 caudal, or slightly nearer the snout, its anterior rays 3.4 in the length. Caudal 

 sharp, lobes equal and as long as the head. Anal not emarginate, short, its 

 longest ray equalling length of ventrals or the head without snout and half 

 the eye. Origin of anal slightly in advance of vertical from last dorsal ray. 



Scales regularly imbricate below the lateral Une from above the ventrals, 

 posteriorly they are deflected or decm-rent to the anal. 



Anal sheath, a single row of oblong scales decreasing in size progressively 

 towards the last rays; a short axillary scale. Lateral line gently decurved 

 throughout its length. 



Silvery; a lateral streak of bright silver from operculimi to caudal; a single 

 round black humeral spot; a horizontally oval spot at the end of the caudal 

 peduncle. 



27. AsTYANAX (Zygogaster) atratoensis Eigenmann. 

 Plate 43, fig. 2. 



Adyanax alralocnsis Eigenm.vnn, Proc. V. S. N. M., 1907, 33, p. 28, fig. 5 (Truando); Eigenmann, 

 Rc])!. Princeton univ. cxped. Patagonia, 1910, 3, p. 433. 



Habitat. — Atrato Basin. 



Specimens examined. 



2.8-3 in the head; interorbital 2.25-2.66 in the head. 



