SOUTH AMERICAN NEMATOGNATHI. 121 



as deep; eye equidistant between end of snont and gill-open- 

 ing. Pectoral spine very feeble, not striate. Head naked 

 above; occipital process short, widely separated from the dorsal 

 spine. Maxillary barbels extend to base of ventrals, postmen- 

 tals to base of pectorals. Depth of body above the anal equals 

 the depth below the dorsal; caudal peduncle as deep as its free 

 portion (behind adipose) is long; caudal fin deeply forked, 

 upper lobe much jDroduced, more than one-fourth of the total 

 length. Brownish above, whitish below. Total length .175 

 m. D. I, 6; A. 10. (Boulenger.) longicauda 93. 



00. Head 4-4^ in the length. 

 p. Adipose fin between 3 and 4 in-the length. 



q. Head three-fourths as wide as long; occipital process mod- 

 erate; eye in anterior portion of the head, 8 in its length, 

 its distance from the snout equals the interocular; depth 

 of intermaxillary band of teeth more than one-sixth of its 

 width. Maxillary barbels reach to or beyond middle of 

 ventrals. Head 4 in the length; depth about 5; depth of 

 caudal peduncle 11. Br. G; D. I, 6; A. 9. (Gill.) 



dorsalis 94. 

 qq. Inner margin of pectoral spine with strong teeth its en- 

 tire length, outer margin smooth or slightly roughened 

 near the base; vent equidistant between base of caudal and 

 base of pectoral sjjine; a dark lateral band; adipose fin 3^ 

 in the length; maxillary barbel reaching to below the an- 

 terior half of the dorsal. Anal rays 13. poei/i 95. 

 pj}- Adipose fin 2J in the length. Inner margin of jiectoral 

 spine roughened on its basal half, thence deejjly grooved to 

 the tip, outer margin with strong recurved notches on its 

 upper two-thirds; vent much nearer to base of pectoral than 

 to the caudal fin; no dark lateral band; maxillary barbel 

 reaching beyond base of ventrals. tenella 96. 



79. Rhamdia breviceps. 



Pimelodus breviceps Kner, SB. Ak. Wien, xxvi, 1857, 418 (Mara- 

 bitanos); Giinther, Cat. Fish. Brit. Mus. v, 122, 1864 (copied). 



Bhamdiahrevicepjs 'Eigenni. & Eigenm. Proc. Cal. Acad. 2d Ser. i, 

 124, 1888, (name only). 



Habitat: Marabitanos. 



This species is known from a single specimen in the 

 museum at Vienna. 



If, as Kner states, this species really does not possess 

 a fontanel nor an occipital process, it of course repre- 

 sents a genus distinct from Rhamdia as here understood. 



