THE UKARI MONKEYS. 181 
frisky little fellow had been reared in the house among the 
children, and allowed to run about freely. . . .” This 
species is rare, even in the limited district which it inhabits. 
A Government official sent six of his most skilful Indians, 
who were absent hunting for three weeks before they obtained 
twelve specimens. 
In reference to the singularly restricted range of these 
Uakaris, Mr. Wallace’s observations in his paper ‘On the 
Monkeys of the Amazon,” before the Zoological Society of 
London, are of great interest. 
“ During my residence,” he says, ‘in the Amazon district, I 
took every opportunity of determining the limits of species, 
and I soon found that the Amazon, the Rio Negro, and the 
Madeira formed the limits beyond which certain species never 
passed. The native hunters are perfectly acquainted with this 
fact, and always cross over the river when they want to pro- 
cure particular animals, which are found even on the river’s 
bank on one side, but never by any chance on the other. On 
approaching the sources of the rivers, they cease to be a bound- 
ary, and most of the species are found on both sides of them. 
Thus several Guiana species come up to the Rio Negro and 
Amazon, but do not pass them ; Brazilian species, on the con- 
trary, reach but do not pass the Amazon to the north. Several 
Ecuador species from the east of the Andes reach down into 
the tongue of land between the Rio Negro and, Upper Ama- 
zon, but pass neither of those rivers, and others from Peru are 
bounded on the north by the Upper Amazon, and on the east 
by the Madeira. ‘Thus there are four districts whose bound- 
aries on one side are determined by the rivers I have men- 
tioned. In going up the Rio Negro, the difference on the two 
sides of the river is very remarkable. 
