SOUTH AMERICAN NEMATOGNATHI. 153 



Ventrals inserted in front of the vertical from the last 

 dorsal ray, their tips sometimes reaching to the anal, 

 1|-1-| in head. 



Pectoral spine, much stronger than dorsal spine and 

 usually shorter, 1J in head, with sharp recurved teeth 

 behind and recurved notches in front. 



Color light brown; a dark lateral band, sometimes con- 

 tinued on head. 



Head 4J; depth 6; Br. 6; D. I, 6: A. 14. 



110, Pimelodella gracilis, 



Pimelodus gracilis Valenciennes, Voy. d'Orbigny, atlas ii, plate ii, 

 fig. 5, 1847; Cuv. & Val. Hist. Nat. Poiss. xv, 181, 1840 

 (Buenos Ayres; Corrientes; Parana); Kner, SB. Ak. Wien, xxvi, 

 418, 1857 (Caicara, Matogrosso; Eio Guapore, Cujaba); Gun- 

 ther, Cat. Fish. Brit. Mus. v, 121, 1864 (copied). 



Pimelodus (Pseudorhamdid) gracilis Steindachner, Flussfische 

 Siidamerika's, i, 9, 1879 (Orinoco near Ciudad Bolivar). 



Pimelodella gracilis Eigeum. & Eigenm. Proc. Cal. Acad. 2d Ser. 

 i, 132, 1888 (Goyaz). 



Habitat: Kivers from the La Plata to the Orinoco. 



Twelve specimens from .11 m. to .17 m. in length. 

 Goyaz, Brazil. Senhor Honorio. 



Body slender, the width at the pectoral about equal to 

 the depth, much compressed toward the tail. Head 

 short, flat above, the profile slightly arched, the width 

 of the head li-l-f in its length; occipital process of the 

 same width throughout, the sides parallel, its width 3J 

 in its length. Fontanel narrow, pointed in front and 

 behind, reaching to the base of the occipital process, a 

 bridge across it above the posterior part of the eye. 



Eye round, 1| in snout, 4 in head, its diameter 

 slightly less than the interorbital. 



Maxillary barbel reaching to tip of ventrals or to be- 

 ginning of anal; mental barbels beyond base of pecto- 

 rals, postmentals to tips of pectorals. 



Lower jaw slightly shorter than the upper, the width 

 at the rictus 2-2 in the head. Intermaxillary band of 



