SOUTH AMERICAN NEMATOGNATHI. 119 



dd. Jaws equal, or the upper jaw longer. 



f. Intermaxillary band of teeth of about eqi;al depth throughout. 

 (J. No dark lateral band. 



h. Pores on the head not aggregated, or at most, 3 in a place; 

 D. I, 6, except sometimes in qttelen. 



i. Maxillary barbels extending beyond middle of adipose tin 

 in the adult. 



j. Vent midway between the bases of caudal and pectoral 

 fins; depth above first anal ray 4 J in the length; depth 

 of caudal peduncle 8 in the length; base of anal oblique. 

 Maxillary barbels extending beyond base of caudal fin. 



obesus 82. 



jj. Vent midway between base of caudal fin and eye. Body 



rather elongate; depth above first anal ray about 6 in 



the length. Eye smaller, about 7 in length of the head. 



sebce 83. 

 jjj. Eye large, 3^ (in young) — 6 in the head. 



sehcf kneri 83a. 

 ii. Maxillary barbels not extending to middle of adipose fin 

 in the adult. 

 k. D. I, 5-8. 



I. Adipose fin 3^-4 in the length. 



m. Eye situated in the middle of the head. Inter- 

 ocular equal to one-half diameter of eye. Posterior 

 nasal opening nearer eye than to the snout. Head 

 flat, the eyes superior; occii^ital process very short. 

 Maxillary barbels reaching tips of pectoral fins; post- 

 mental barbels to base of pectorals. Dorsal spine 

 little more than half as high as the rays; adipose fin 

 originates above tips of ventrals, twice as long as the 

 dorsal fin; caudal forked, upper lobe longer than the 

 lower; anal under middle of adipose; pectoral spine 

 strongly serrated, especially along its outer margin. 

 Head more than 5 in the total length. Br. 6; D. I, 6; 

 A. 11. (Milller & Troschel.) foina 84. 



mm. Eye in the anterior half of the head. 



n. Distance of adipose from dorsal fin equals |-| its 

 own length. Maxillary barbels extending on to 

 root of ventrals; intermaxillary band of teeth 8 

 times as wide as deep; eye 2-3 in interocular, 6 in 

 head; the eye occupies the third sixth of the head. 

 Pectoral spine 2.J in head, slightly serrated along 

 both edges; caudal fin cleft to the base, the ujiper 

 lobe more pointed than the lower. Head 4f in the 

 length; depth 64; D. I, 6; A. 12. (Gtinther.) 



h limit is 85. 



