Order I. Nematognathi. 



The Catfishes. 



Fishes without scales, the body smooth or provided with bony 

 plates, and with whiskers about the mouth. Parietals and supra- 

 occipitals confluent; the four anterior vertebrae co-ossified; no meso- 

 pterygium; suboperculum wanting or modified into the uppermost 

 branchiostegal. 



Family I. Siluridse. 



Body naked or with a single series of plates along middle of sides; 

 mouth terminal or subterminal; opercle well developed; gill-openings 

 usually wide; maxillary a mere vestige; caudal vertebrae not compressed; 

 air-bladder well developed, lying free in the abdominal cavity; dorsal 

 fin over abdominal portion of vertebral column; adipose fin present, 

 long or short; anal fin not very long, its origin far behind that of dorsal. 



KEY TO THE GENERA. 



a. Eye with a free orbital margin; adipose fin longer than anal. 



b. Occipital process failing to reach dorsal plate; adipose fin much 

 longer than head. Rhamdia, p. 239. 



bb. Occipital process reaching dorsal plate; adipose fin shorter or not 

 very much longer than head. 



c. Fontanel not continued beyond eyes; humeral process spine-like. 



Pimelodus, p. 241. 



cc. Fontanel continued beyond eyes; humeral process broad, not 



spine-like. Pimelodella, p. 242. 



aa. Eye without a free orbital margin; adipose fin shorter than anal. 



d. Barbels 6, a pair of maxillary barbels and 2 pairs of mandibular 

 barbels; caudal fin obliquely truncate, emarginate or rather 

 deeply concave. Trachycorystes , p. 243. 



dd. Maxillary barbels present, very small, especially in the female; 

 no mandibular barbels; caudal fin forked. Ageneiosus, p. 244. 



1. Genus Rhamdia Bleeker. 



Rhamdia Bleeker, Verhand. Natuurk. Vereen. Nederl. Indie, IV, 1858, 

 197 (sp.); Bleeker, Nederl. Tijdschr. Dierk., I, 1863, loi (type 

 Pimelodus quelen Quoy & Gaimard). 



239 



