Pearson: Fishes of the Rio Beni Basin 
5 
were new, one of them representing a new genus. The others 
are species widely distributed in the Andes at the altitude of 
Espia. 
After a few days at Espia the expedition proceeded by 
balsas to Huachi, altitude 2,235 feet. Huachi overlooks the 
junction of the Bopi and Cochabamba rivers which here form 
the Beni. The two rivers have cut a valley about three miles 
wide. This valley offers a variety of habitats, but no species 
peculiar to the lowlands were found. In this locality a month 
was spent collecting up and down rivers, in side streams, cut- 
off streams, pools, and in the main river. 
2. Upper Beni, below Huachi 
From Huachi the expedition continued to Rurrenabaque. 
Rurrenabaque is located at the mouth of a canon cut thru the 
last ridge of the Andean foothills. Here the country opens 
out into the Amazonian lowlands. Until logs obstructed the 
river launches came to this point. Now they are met by 
balsas a league below. 
Two side trips, each lasting a month, were made from here. 
The first (October 15 to November 15) went by means of 
ox carts to Reyes and Lake Rogoagua. This region is pampa 
and contains many lagoons and swamps which offered excel- 
lent collecting grounds. Lake Rogoagua (muddy water) is 
all that the name implies. It is shallow, and the least wind 
