246 THE AMERICAN CHARACIDAE. 



convex. Interorbital much broader than the eye in adult. Frontal fontanel a 

 little narrower than the parietal. Margin of second suborbital very convex; 

 leaving a naked area, which is widest below. Maxillary equal to the eye; 

 four or five teeth in the front row of the premaxillary, the third withdrawn from 

 the line of the rest; five graduated teeth in the second row, their denticles in 

 shallow crescents, maxillary with 2 or 3 minute teeth. Dentary with four 

 large teeth abruptly followed by smaller ones on the sides. 



Gill-rakers 8+11. 



Scales of the sides regularly imbricate, a few interpolated scales over the 

 anal muscles. 



Anal sheath of a single row of scales along the base of the anterior rays; 

 caudal naked; a well-developed axillary scale. Lateral line but little deciu-ved. 

 Each scale of the sides with a few nearly parallel striae. 



Dorsal but little farther from snout than the ventral, nearer snout than 

 caudal, its margin rounded, the highest ray about 3.75 in the length, the penulti- 

 mate a little less than half as long as the highest. Anal emarginate, the 2nd and 

 10th reaching the base of the 18th when depressed; first anal ray below or behind 

 the base of the last dorsal ray. Ventrals not reaching anal, pectorals to ventrals. 



Highly iridescent, blue above, greenish to silvery below; a club-shaped 

 horizontal humeral spot, its pointed anterior end from the upper margin of the 

 first scale of the lateral line along the row of scales above the lateral line to 

 above the 5th scale of the line; a dark vertical bar crossing the opercle, followed 

 by a light bar, a second dark bar across the posterior part of the humeral spot, 

 a second light bar and then a third dark bar shading into the profusely dotted 

 sides. Cheeks profusely dotted; a dark median line, most prominent in young 

 specimens preserved in formalin; this line not extending along the sides of the 

 caudal peduncle; a black spot at the base of the caudal, its margins shading 

 into the dusky caudal but not definitely continued to the end of the middle rays. 

 These markings fading with age. In life all fins but pectorals tinged with orange 

 or brick-red. 



13. AsTYANAX (PoECiLURiCHTHYs) ANTERIOR Eigenmaun. 

 Plate 40, fig. 2. 



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

 1910, 3, p. 432, 



Habitat. — Tabatinga. 



