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 



