THE LIFE OF MAMMALS 
advantage to the animal either when sitting in repose on the branch of a 
_tree, or when in its journey onwards in the gloomy recesses of the wilder- 
ness. You may see this [spider] monkey catching hold of the branches 
with its hands, and at the same moment twisting its tail around one of them 
as if in want of additional support; and this prehensile tail is sufficiently 
strong to hold the animal in its place, even when all its four limbs are de- 
tached from the tree, so that it can swing to and fro and amuse itself 
solely through the instrumentality of its prehensile tail, which, by the way, 
would be of no manner of use to it did accident or misfortune force the 
monkey to take up a temporary abode on the ground.” 
Nevertheless, as Dr. Lydekker remarks, since the teetees have no pre- 
hensibility in the tail, and others, as ooakaris, lack a tail of practicable 
length, it is clear that the prehensile organ must be regarded as a kind of 
luxury. “Indeed,” as he observes, ‘‘the whole question as to the reason 
why some monkeys have long tails, others short tails, and others again no 
tails at all, is involved in great obscurity.” But that is true of many other 
features of animal structure and economy more important than tails! 
The most famil- 
jar and character- 
istic of the American 
monkeys are the 
capuchins or sapa- 
jous of the genus 
Cebus, eighteen spe- 
cies of which are 
catalogued between 
Paraguay and Costa 
Rica, though none 
wanders throughout 
this wide range, and 
only one is known 
in Central America; 
but they are so 
So closely alike in 
Copyright, N. Y. Zodl. Socicty. Santor, Phot. Structure and hab- 
A CAPUCHIN, its, and so variable 
38 
