6 FISHES OF WESTERN SOUTH AMERICA 
Huallaga and Ucayali Rivers from their sources to the neighborhood of 2,000 
feet above sea level. 
In May of 1920 I started on the so-called Centennial Expedition of Indiana 
University to carry the survey of the fish fauna to the lower levels of the rivers 
of eastern Peru. The expedition was assisted by a grant from the Bache Fund 
of the National Academy of Sciences, and by the hearty cooperation of the 
Peruvian government, which provided free transportation and other assistance 
within Peru. 
The writer traveled alone, so far as the English-speaking personnel of the 
expedition is concerned, depending solely upon local aid. At times help was 
volunteered by interested individuals or solicited from the local authorities, 
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Fic. 3. The upper Mantaro near Jauja, about 11000 feet above sea level. This portion of the 
river pertains to the temperate life zone, and to the area of the upland fish fauna. 
civil and military. Three weeks of the initial portion of the trip (from the 
Perené to the Ucayali) were spent in company with Professor J. Chester 
Bradley and Dr. W. T. M. Forbes, of the Cornell Entomological Expedition. 
The plan of the present expedition has been to collect as exhaustively as 
possible the fishes of a few suitable, representative localities in the basins 
of the above-named rivers, comprised for the most part within the great 
Department of Loreto. Entering by Lima, Tarma and La Merced, the writer 
began where the Irwin Expedition left off two years ago, and crossed to the 
head of navigation of the Pichis-Pachitea-Ucayali system by the Via Central. 
Ten days were required to traverse the final 200 kilometers of this atrocious 
trail. It is an endless succession of mudholes, yet the principal and almost 
sole means of communication between coastal Peru and her transandine 
provinces. 
