THE CATFISHES OF VENEZUELA — SCHULTZ 233 



Head greatly depressed ; wide bands of villiform teeth on premaxil- 

 laries, vomer, palatines, and dentaiy. The arrangement of the teeth 

 in roof of mouth is illustrated in figure 3, g. A broad, depressed snout, 

 projecting a little beyond the lower jaw; nostrils widely separated, 

 far forward on snout; eye superior; extremely long maxillary barbels, 

 ossified as far back as opposite end of dorsal fin, then becoming flexible, 

 band-shaped to opposite caudal iin base, thence tapering to a fine, 

 hairlike filament opposite rear of caudal fin and continued beyond 

 tips of rays of caudal fin; outer pair of mental barbels not quite so 

 long as length of snout ; mner or anterior pair of mental barbels about 

 half length of outer or posterior ones; supraoccipital moderately 

 broad, meeting the predorsal plate; a wide fontanel beginning on snout 

 continues in middorsal line to behind eye where it becom.es a narrow 

 groove in the supraoccipital process; center of eye a little closer to 

 tip of supraoccipital process than to tip of snout, and the width of 

 the interorbital space closer to posterior end of gill cover than to tip 

 of snout; interorbital space a little concave; pectoral spines strong, 

 wide, with weak antrorse teeth on anterior m.argin and strong retrorse 

 teeth on posterior margin, this spine as long as snout and eye together; 

 dorsal spine strong, smooth anteriorly, but toothed along its posterior 

 margin; gill membranes extending forward, free from the isthmus; a 

 pouch in front of isthmus between bases of mental barbels; a large 

 dermal fold on inside of gill cover; gill rakers bony, about 5 + 14; 

 air bladder laige, extending as far back as opposite pelvic girdle; 

 snout projecting beyond tip of lower jaw; width of head at base of 

 pectorals one-half distance from tip of snout to rear of supraoccipital 

 process, or equal to distance from tip of snout to center of eye; base 

 of adipose fin longer than anal fin base; caudal peduncle slender, 

 caudal fin deeply forked; upper lobe with the upper ray produced, 

 more or less filamentous; contour of ventral surface from pelvics to 

 tip of snout flat, mostly in same plane. 



KEY TO THE SPECIES OF PLATYSILURUS 



la. Total length of adipose fin 2.1 in snout to dorsal origin; anal origin barely 

 behind a vertical line through adipose origin; pelvic insertion under bases 

 of third to fourth dorsal soft rays and equal distaiice between tip of snout and 

 midbase of caudal fin rays; head V/z in standard length; shortest midcau- 

 dal fin rays 2 times in eye to dorsal origin. .Platysilurusbarbatus Haseman 



16. Total length of adipose fin 2.3 to 2.7 in snout to dorsal origin; anal origin 

 distinctly behind a vertical line through adipose origin; pelvic insertion 

 under bases of 6 to 6 soft rays of dorsal and equal distance between base of 

 maxillary barbel and midbase of caudal fin; head about 3 in standard length; 

 shortest midcaudal fin ray about 3 times in distance from rear of eye to 

 dorsal origin Platysilurus malarmo, new species 



