114 Annals of the Carnegie Museum. 



5 Pimelodella gracilis (Valenciennes) (Plate XXXII., Fig. 2). 



One specimen from Corumba (352), and another from Laguna 

 Ipacarai (450). 



6. Pimelodella lateristriga (Miiller and Troschel). 

 Seven specimens from Villa Rica (469). 



7. Pimelodella mucosa Eigenmann and Ward sp. nov. (Plate XXXII., 



Fig. 1). 

 Type No. 10125. One specimen from Bahia Negra (399). This 

 species is most nearly allied to P. eigenmanni and buckleyi from which 

 it may be distinguished as follows : 



a. Lower caudal lobe the longer. 



b. Maxillary barbel reaching to middle of caudal ; postmental barbel to middle 



of pectoral spine ; pectoral spine curved, with about fifteen straight, feeble 

 spines on its posterior surface, anterior surface with minute denticulations 

 along basal part and feeble recurved hooks near its tip, \yl in the head. 



mucosa, 

 aa. Upper caudal lobe the longer. 



c. Maxillary barbel reaching beyond origin of anal ; postmental about to middle 



of pectorals ; pectoral spine as long as the distance between base of maxil- 

 lary barbel and the opercular border, its inner edge distinctly though 



feebly serrate ; adipose dorsal 3| to 4 in the length eigenmanni. 



cc. Maxillary barbel reaching to origin of anal; postmental to tip of pectoral; 

 pectoral spine as long as the distance from the anterior border of eye to 

 the opercular margin, practically smooth on its inner edge ; adipose fin a 

 little more than ^3 in the total length buckleyi. 



Body compressed posteriorly; head sub-conical, depressed in front, 

 its width 1J/3 in its length, its -depth at the base of occipital process 

 1%, its width at the angle of the mouth 2fi in the head; occipital 

 process rather slender, its width at base 2^ in its length ; maxillary 

 barbel reaching to middle of caudal ; mental barbel to operculum ; 

 postmental to middle of pectoral. Gill-membranes separate to below 

 anterior margin of eye ; very conspicuous pits along either side of the 

 lower surface of the head. Eye if in the snout, 354 in the head, 

 1^ in interorbital, slightly nearer to posterior margin of operculum 

 than to snout. Dorsal spine equidistant from snout and anal ; its 

 highest rays equal in height to the head in length. Adipose dorsal 

 3% in the length, its distance from the dorsal fin being \ x /i in the 

 length of the latter. Caudal long and deeply forked, the lower lobe 

 wider and longer than the upper, 3^ in the length. Anal rounded, 

 its longest ray i|- in the head. Ventrals inserted on a vertical line 

 with fourth dorsal ray, \y 2 in length of head; pectoral spine 1% in 



