244 THE AMERICAN CHARACIDAE. 



11. AsTYANAX (PoECiLURiCHTHYs) BOURGETi Eigenmann. 

 Plate 40, fig. 1. 



Astyanax bourgeti Eigenmann, Bull. M. C. Z., 1908, 52, p. 95; Rept. Princeton univ. exped. Patagonia, 

 1910, 3, p. 432. 



One specimen. 20768 part Type. 92 mm. Tabatinga. Bourget. 



A well-marked species, differing from all others in the genus in its black 

 lower fins. 



Head 3^; depth 2^; D. 11; A. 34; scales 12-53-9; eye a little less than 

 one third of the length of the head; interorbital 2.47. 



Compressed; ventral profile regularly arched to the caudal peduncle; 

 dorsal profile descending from the origin of the dorsal in both directions, anterior 

 profile more arched above, depressed over the eye. Preventral area rounded, 

 without a median series of scales, postventral area compressed. Predorsal line 

 probably naked to near the dorsal. 



Occipital process one fourth of the distance from its base to the dorsal, 

 bordered by about 5 scales. Interorbital broad, smoothly arched but not 

 greatly elevated. Anterior fontanel not much shorter than the posterior, 

 exclusive of the groove on the occipital. Second suborbital leaving a rather 

 wide naked area. Snout pointed. Maxillary equals length of eye. Mandible 

 2^ in head. Five 3-pointed teeth equidistant from each other in the front 

 series of the premaxillary, the middle one somewhat withdrawn from the line, 

 six teeth in the second row, their denticles in a nearly straight line. Maxillary 

 with two minute teeth on one side and three on the other; five graduated teeth 

 on each side of the lower jaw, followed by a series of minute teeth. 



Scales regularly imbricate except over anal and the preventral region; 

 three series of scales below the lateral line parallel with it, some interpolated 

 rows below the thu'd row above the anal; lateral line but little decurved. 



Origin of dorsal equidistant from tip of snout and caudal, its highest ray 

 about one fourth of the length. Origin of anal and base of last dorsal ray equidis- 

 tant from tip of snout ; base of anal equals distance of dorsal from caudal. Origin 

 of ventrals and a point equal to two thirds of the base of the dorsal in front 

 of the first ray equidistant from the tip of the snout and last but 7th anal ray. 

 Ventrals reaching base of fourth anal ray. Pectorals to the fourth row of scales 

 behind the origin of the ventrals. 



A large, well-defined, horizontally ovate humeral spot on upper part of the 



