DRIVER— THE LUCIOPIMELODIN^. 453 



band of premaxillary teeth. The band is rounded at the outer end 

 instead of prolonged into a sharp angle as in pati. 



Still later Eigenmann^- described Megaloneina xanthum from 

 the upper Magdalena River of Columbia.^^ 



Key to tpie Genera and Species of Luciopimelodin.^. 



a. Mouth terminal, the lower jaw pointed, its tip extending to the tip of the 

 upper jaw; premaxillary band of teeth with a long, backward project- 

 ing angle ; adipose fin beginning at tip of last dorsal ray, its length little 

 more than three in the length ; snout greatly depressed ; depth of head 

 three in its length ; post-mental barbels extending past base of the anal, 

 A. 12; eye 10 in head, 4.5 in snout, 2.33 in interorbital. (Based on a 



specimen 230 mm. to base of caudal.) (Luciopimelodus.) pati. 



aa. Jaws subequal, premaxillary band of teeth without a backward projecting 

 angle. 

 b. Space between adipose and base of last dorsal ray considerably greater 



than base of dorsal (Megalonema.) 



c. Head 4: depth 6; adipose 4 in length; dorsal I, 6; A. 12; eye 2.5 



in snout, 5 in head platamim. 



cc. Head 3.66 in the length ; depth 5.5 ; adipose 4 in the length ; dorsal 



I, 6 ; A. II ; eye 2 in the snout, 5 in head platyccphalum. 



ccc. Head 4; depth 5.33; A. 9; adipose 4.95 in the length; eye 4 in 

 the head, .75 in the interorbital; snout depressed, width of 

 head at the rictus 2 in the length of the head; maxillary barbel 

 reaching middle or beyond tip of pectoral ; teeth in a very 

 narrow band ; fontanel reaching base of occipital crest which 

 is minute ; the first dorsal ray slender, a little longer than the 

 head. (Based on a specimen 38 mm. in length.) 



pauc'iradlatum. 



bb. Space between adipose and base of last dorsal ray much shorter than 



the base of the dorsal, post-mental barbel not far behind the 



mental (Perugia.) 



d. Lower jaw but a little shorter than the upper, premaxillary band 

 of teeth terminal, partly exposed when mouth is closed; fon- 

 tanel increasing in width backward to behind the eye ; a small 

 fontanel at the base of the occipital process ; head 5 in the 



length ; depth 6 ; dorsal I, 6 ; A. 11 agassi::ii. 



dd. Snout much projecting, the mouth inferior; the premaxillary band 

 of teeth very narrow; maxillary barbel extending past base 

 of anal ; adipose 2.5 in the length ; fontanel wider behind than 

 in front, extending to the posterior edge of eye ; small fon- 

 tanel at the base of the occipital process; A. 11 xanthus. 



12 Ind. Univ. Studies, No. 16, Dec, 1912, p. 16. 



^3 The species of Megalonema described by Meek from the Tuyra River 

 belong to the genus Pimclodus. 



