Indiana University Studies 
Vol. XI 
December, 1924 
Study No. 64 
THE FISHES OF THE EASTERN SLOPE OF THE 
ANDES. I. THE FISHES OF THE RIO BENI BASIN, 
BOLIVIA, COLLECTED BY THE MULFORD EXPEDI- 
TION. By Nathan Everett Pearson, A.M., Assistant in 
Zoology, Indiana University. 
The present study continues the discussion of the distribution of the 
fresh- water fishes of western South America begun in Study No. 45 and 
continued in Study No. 46 and No. 47. Other articles on the same sub- 
ject are: “The Fish Fauna of the Cordillera of Bogota” (Journal Wash- 
ington Academy of Sciences X, pp. 460-468, October 4, 1920) ; “The 
Origin and Distribution of the Genera of the Fishes of South America 
west of the Maracaibo, Orinoco, Amazon, and Titicaca Basins” (Proc. Am. 
Philos. Soc. LX, 1921) ; “The Nature and Origin of the Fishes of the 
Pacific Slope of Ecuador, Peru, and Chili” (Proc. Am. Philos. Soc., LX, 
1921) ; “The Fishes of the Pacific Slope of South America and the Bear- 
ing of Their Distribution on the History of the Development of the To- 
pography of Peru, Ecuador, and W estern Colombia” (Am. Nat., LVII, 
1923). 
An account of the fishes of Western South America, Part I, has been 
published in the Memoirs of the Carnegie Museum, IX, 1922, and Part II 
is in press. 
