SOUTPI AMERICAN NEMATOGNATHI. 121 



as deep; eye equidistant between end of snout 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 produced, more than one-fourth of the*total 

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

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



oo. Head 4-4J 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. 6; 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 spine; 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. poeyi 95. 

 pp. Adipose fin 2 in the length. Inner margin of pectoral 

 spine roughened 011 its basal half, thence deeply 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); Giiiither, Cat. Fish. Brit. Mus. v, 122, 1864 (copied). 



Rhamdia breviceps Eigenrn. & Eigenrn. 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. 



