Order I. Nematognathi. 
Tue 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 vertebre co-ossified; no meso- 
pterygium; suboperculum wanting or modified into the uppermost 
branchiostegal. 
Family I. Siluridz. 
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 vertebre 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. 
a. 
b 
bb. 
KEY TO THE GENERA. 
Eye with a free orbital margin; adipose fin longer than anal. 
Occipital process failing to reach dorsal plate; adipose fin much 
longer than head. Rhamdia, p. 239. 
Occipital process reaching dorsal plate; adipose fin shorter or not 
very much longer than head. 
Fontanel not continued beyond eyes; humeral process spine-like. 
Pimelodus, p. 241. 
Fontanel continued beyond eyes; humeral process broad, not 
spine-like. Pimelodella, p. 242. 
Eye without a free orbital margin; adipose fin shorter than anal. 
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. 
. 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, ror (type 
Pimelodus quelen Quoy & Gaimard). 
239 
