148 MOSTLY MAMMALS 
In ordinary five-fingered monkeys, whether they hail 
from the Old World or from the New, the foregoing type 
of eminences is very constant. This is well exemplified 
by the impression of the hand of one of the South American 
capuchin monkeys (fig. A). Here, however, the fingers 
are much longer and more slender than in the Old World 
macaque. In consequence of this the bulbs of the fingers 
are much less developed, so that it was found impossible 
to get a good impression of them. These features are 
even more developed in the hand of the tiny American 
marmosets (fig. D), in which the digits are more like 
claws than fingers, and consequently afford only a narrow 
and blurred impression. A peculiarity of the marmoset 
hand-print is to be found in the circumstance that the 
radial eminence has come up to form an arch with the three 
interdigital elevations, and that the ulnar elevation and 
pattern are obsolete. Seeing how comparatively wide apart 
from one another (both zoologically and geographically) are 
the ordinary monkeys of the Old and New Worlds, it is 
not a little remarkable that the palm-print of the macaque 
should be so strikingly like that of the capuchin. 
This similarity (since everything in nature has a use) 
suggests that the patterns on the hands of these two 
monkeys are due to the same physiological cause; and 
we have now to inquire what that cause is. The best 
clue to the problem seems to be afforded, somewhat 
strangely, by the tails of such of the South American 
monkeys as are endowed with prehensile power in those 
appendages ; confirmatory evidence being likewise afforded 
by the prehensile tails of the American opossums and 
tree-porcupines, as well as by those of the Australian 
phalangers. In all these animals the naked, grasping 
portion of the tail, which is situated at the extremity, is 
