32 
Indiana University Studies 
third ray the longest, not nearly reaching the caudal fulcra 
when depressed; height of the dorsal in some cases equalling 
the depth of the body, the third ray the longest, not quite 
reaching the tip of the last ray when depressed, the base equal 
to .75 the distance from the last ray to the adipose. 
Adults with a dark line beginning in a spot just back of the 
opercle and extending to the base of the middle caudal rays; 
in the young this line is silvery; all fins tinged with purple; 
the dorsal with a narrow dark bar which may or may not ex- 
tend the entire width; the other fins unmarked. The young 
have the back brown with 8 wide bars which extend to the 
lateral line or beyond ; a dot at the base of the middle caudal 
rays ; the dorsal without the dark bar. 
Subfamily pyrrhulinin^e. 
Pyrrhulina beni Pearson, sp. nov. 
17346, 3, cotypes, 42-46 mm., Ivon. Feb., 1922. 
Very closely related to P. brevis from which it differs by 
possessing fewer scales, a less deep body and caudal peduncle. 
It differs from P. australis by possessing a less deep caudal 
peduncle and a more narrow interorbital. 
Head 3.75 to 3.8; depth 4.5; D.10; A. 12; eye 2.8 to 3; 
scales 23 or 24, 6 in a vertical series ; interorbital 2.66 in 
head, caudal peduncle 2/5 of head; snout less than the 
diameter of the eye ; origin of the dorsal equidistant from head 
and base of the caudal. 
A black stripe from the lower jaw thru the eye to the end 
of the operculum; a broad dark band from head to caudal, 
narrower posteriorly ; a black spot on the dorsal fin. 
Subfarqily CHEIRODONTIN^E. 
Aphyocharax dentatus Eigenmann & Kennedy. 
17214, 36, 60-98 mm., Pena Colorado, Upper Beni. Sept., 1921. 
17337, 7, 54-65 mm., Huachi. Sept., 1921. 
17338, 34, 55-70 mm., Rurrenabaque. Oct., 1921. 
17339, 35, 50-78 mm., Rio Iniqui, Upper Beni. Sept., 1921. 
This species has heretofore been described only from the 
Paraguay system. Two specimens from 17214 have some of 
the teeth bifid in the premaxillary and mandibular bones. 
The maxillary bone is slightly shorter than the typical A. den- 
tatus. 
