SOUTH AALERICAN NEMATOGNATHI. 121 



width, above ventrals, 1| iii the greatest depth. Head short, 

 flat beh)w, regularly convex above; profile very steep and 

 almost straight. The thick skin obliterates the outlines of 

 all the bones. Occipital process long and narrow, not 

 reaching the dorsal plate. 



Eye small, its anterior margin equidistant from the snout 

 and the free border of the opercle, its diameter 4 in the 

 snout, 8 in the head, 2J in the interocular. Posterior nasal 

 opening a transverse slit. 



Maxillary barbels reaching to or beyond the end of the 

 adipose fin; mental barbels reaching beyond base of the 

 pectorals, the post-mentals beyond their tips. 



Mouth entirely inferior, the snout projecting beyond 

 it more than one diameter of the eye; lower jaw weak, the 

 teeth scarcely evident, in a very narrow baud; the teeth of 

 upper jaw in a somewhat wider band. 



Gill-rakers 7+17. 



Distance of dorsal fin from tip of snout 3| in the length; 

 first dorsal ray high and slender, scarcely spinous; the free 

 margin of the fin straight. Adipose fin beginning imme- 

 diately behind the dorsal, its base 2 in the length. 



Caudal fin deeply forked, the lobes of equal length, 

 longer than the head. 



Fourth anal ray highest, higher than the fin's base, 2 in 

 the length of the head. 



Ventrals inserted little nearer anal tin than to tip of 

 snout, I5 in the head. 



First pectoral ray scarcely spinous, slightly serrate on its 

 inner margin, about as long as the head. 



Axil and humeral region blackish, otherwise uniform 

 yellowish. 



Head 5^; depth 5|; depth of peduncle 13; Br. 9; D. 7; 

 A. 12. 



III. PiKiNAMPus Bleeker. 

 4. Pirinampus pirinampu (Spix). 



? Pimdodus barbancho Humboldt; Pirinampus typus Bleeker. 

 Locality: Cameta. 



