14 
Indiana University Studies 
aa. Adipose fin more than 3 in the length. 
d. Dorsal spine in the males produced into a heavy filament; 
head 4.1 to 4.2; adipose 3.6 to 3.75; maxillary barbels 
reaching tip of ventrals or to base of anal. 
4. griffini. 
dd. Dorsal spine not produced into a heavy filament; head 4.2 
to 4.7 usually 4.5 or more; adipose 4 to 4.2 in the 
length; maxillary barbels reaching base or tip of 
ventrals. 
5. laticeps australis . 
Pimelodella buckleyi (Boulenger). 
17087, 1, 95 mm., Ixiamas. Dec., 1921. 
Pimelodella gracilis (C. & V.). 
17084, 12, 34-110 mm., Lake Rogoagua. Nov., 1921. 
17085 and 17094, 10, 120-160 mm., Huachi. Aug., 1921. 
17092, 13, 56-85 mm., Rurrenabaque. Oct., 1921. 
17093, 17, 65-145 mm., Pena Colorado, Huachi. Sept., 1921. 
17085 probably represent the true P . gracilis. 17092, 17093 
and 17084 have a longer and weaker dorsal spine which is 
prolonged in a filament in some specimens. It is irregular 
and much weaker than that of P. griffini and seems close to 
Ribeiro’s P. txnioptera. 17084 have the upper caudal lobe 
only slightly prolonged. 
Pimelodella roccae Eigenmann MS. 
17088, 6, 115-125 mm., Pool, Lower Bopi. Sept., 1921. 
17089, 13, 55-125 mm., Popoi River, Upper Beni. Sept., 1921. 
17090, 12, 68-115 mm., Rio Colorado, Lower Bopi. Sept., 1921. 
17091, 11, 68-140 mm., Huachi. Aug., 1921. 
This species is described in a MS. account of the fishes of 
the Rio Urubamba. 
A lateral band is present in some ; in others it is indistinct. 
Those caught in forest pools were almost black. Those caught 
in open pools and in streams were light. The length of the 
maxillary barbels vary, the tips reaching from the pectoral 
region to the anal or slightly beyond. Usually however they 
extend to the anal or slightly beyond. The coalescence of the 
outer spines may be complete so that the edge is smooth, or 
there may be an incomplete coalescence with indentations. 
This together with the weak nature of the spines make the 
species run into P. buckleyi. 
