Pearson: Fishes of the Rio Beni Basin 
31 
All the above specimens differ from the Guiana material 
in the following respects: 
Guiana 
Anal obliquely truncate. 
Tip of longest anal ray extend- 
ing slightly beyond the last 
scales of lower caudal lobe. 
Dorsal narrowly rounded. 
17222, 2, 55 and 58 mm., Cachuela 
Rio Beni 
Anal rounded. 
Tip of longest anal ray not ex- 
tending beyond last scales of 
lower caudal lobe. 
Dorsal widely rounded. 
Esperanza. Mar., 1922. 
These specimens are young with the conspicuous juvenile 
colors. 
Leporinus y-ophorus Eigenmann. 
17224, 1, 190 mm., Ivon. Feb., 1922. 
The above specimen differs from the type by having the 
fourth and fifth transverse bars united to form a “y” as well 
as the second and third. 
Subfamily nannostomatule. 
Characidium fasciatum Reinhardt. 
17236, 29, 25-34 mm., Cachuela Esperanza. Mar., 1922. 
17237, 3, 40-58 mm., Rio Iniqui, Upper Beni. Sept., 1921. 
17238, 10, 28-35 mm., Lagoons, Lake Rogoagua. Nov., 1921. 
17239, 14, 46-56 mm., Tumupasa. Dec., 1921. 
17240, 35, 32-75 mm., Popoi River, Upper Beni. Sept., 1921. 
17241, 28, 43-65 mm., Rio Colorado, Lower Bopi. Sept., 1921. 
Characidium bolivianum Pearson, sp. nov. Plate IX, fig. 3. 
17301, 13, cotypes; 42-63 mm., Popoi River, Upper Beni. Sept., 1921. 
17300, 22, 38-62 mm., Rio Colorado, Lower Bopi. Sept., 1921. 
17302, 2, 45 and 48 mm., Tumupasa. Dec., 1921. Females with lateral 
lines 32 and 34, otherwise the same. 
This species differs from C. phoxocephalum by possessing a 
narrower interorbital space and a narrower head. It differs 
from C. zebra by possessing a smaller eye. The young very 
closely resemble C. fasciatum. 
Head 4 to 4i/ 2 ; depth 4 6/7 to 5 1/3; D.ll; A.8; eye 4 to 
414 ; scales 4 — 36 to 37 — 2 or 21 / 2 ; bony interorbital about 2 
in the eye ; teeth conical or with a tiny cusp on each side of the 
main cusp ; pectorals may or may not reach the ventrals, the 
tips of the outer rays not thickened ; ventrals almost reaching 
the anal, occasionally reaching the anal; anal rounded, the 
