

SOUTH AMERICAN NEMATOGNATHI. 327 



/. Caudal emarginate; D. 14; gill-membrane free from the isthmus; 



upper maxillary barbels reaching pectorals. Origin of dorsal 



equidistant from tip of caudal and occiput. Distance of anal 



from base of caudal 5 in the length. areolatum 259. 



fj. Caudal truncate or rounded. 



(/. First ray of the pectoral prolonged except in very young. 

 h. Teeth in broad bands in both jaws.* 



i. Maxillary barbels reaching to the preopercle; D. 13; A. 

 11. rivulatum 260. 



ii. Maxillary barbels reaching beyond the gill-opening; D. 

 1 1 ; A . 9 . brasiliensis 26 1 . 



hh. Teeth in two series in each jaw (?). 

 j. Head narrowed forward, heart-shaped, scarcely wider 

 than long; upper maxillary barbels reaching to base of 

 pectoral; origin of anal below end of dorsal; a dark lat- 

 eral band, two series of spots above it; top of head spot- 

 ted. Head 7; D. 8; A. 6. (Kner & Steindachner.) 



lamia 262. 



jj. Head of uniform width; width of mouth more than half 

 length of head. Teeth in the anterior series of each jaw 

 compressed. Maxillary barbels reaching beyond base of 

 pectoral. Head and body with numerous dark spots. 

 Head 7; D. 9; A. 7. (Kner & Steindachner.) laticeps 263. 

 <jg. First ray of the pectoral not prolonged; none of the bar- 

 bels reaching gill-opening. oroyce 264. 

 ee. Dorsal entirely in front of the anal. 

 k. Caudal rounded. 



I. Yellowish, upper half of sides and the back thickly punctate 

 with darker. (Castelnau.) punclatissimum 265. 



II. Uniform brown, darkest on the back. knerii 266. 

 kk. Caudal emarginate. 



m. Back and sides profusely spotted; first pectoral ray pro- 

 longed. 

 n. Dorsal behind the base of the ventrals. 



o. Head longer than broad by a diameter of the eye. 

 p. Spots as large as or larger than the eye. dispar 267. 

 pp. Spots much smaller than the eye. 



dispar punctulatum 267a. 



oo. Head as long as broad; upper maxillary barbel extend- 

 ing to the base of the pectoral. Head 6J; D. 8; A. 6. 

 (Boulenger.) niyromacnlatum 268. 



nn. Dorsal partly over the base of the ventrals; D. 8; A. 1:2. 

 (Cope.) pardum 269. 



* Tridiomycterus pneyanus Cope, probably belongs h*re; as the shape of the caudal and 

 length of the barbels are not given, we have not been able to give it a place in this key. 



