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The American monkeys, on the other hand, with the exception of 

 the marmosets, have four additional grinding-teeth (one in each jaw 

 on either side), and none of them have callosities or cheek-pouches. 

 They never have prominent snouts like the baboons ; their nostrils are 

 placed wide apart and open sideways on the face ; the tail, though 

 sometimes short, is never quite absent ; and the thumb bends the same 

 way as the fingers, is generally very short and weak, and is often quite 

 wanting. We thus see that these American monkeys differ in a great 

 number of characters from those of the Eastern hemisphere ; and they 

 have this further peculiarity, that many of them have prehensile or 

 grasping tails, which are never found in the monkeys of any other 

 country. This curious organ serves the purpose of a fifth hand. It 

 has so much muscular power that the animal can hang by it easily 

 with the tip curled round a branch, while it can also be used to pick 

 up small objects with almost as much ease and exactness as an ele- 

 phant's trunk. In those species which have it most perfectly formed 

 it is very long and powerful, and the end has the under-side cpvered 

 with bare skin, exactly resembling that of the finger or palm of the 

 hand, and apparently equally sensitive. One of the common kinds of 

 monkeys that accompany street organ-players has a prehensile tail, but 

 not of the most perfect kind ; since in this species the tail is entirely 

 clad with hair to the tip, and seems to be used chiefly to steady the 

 animal when sitting on a branch by being twisted round another 

 branch near it. The statement is often erroneously made that all 

 American monkeys have prehensile tails ; but the fact is that rather 

 less than half the known kinds have them so, the remainder having 

 this organ either short and bushy or long and slender, but entirely 

 without any power of grasping. All prehensile-tailed monkeys are 

 American, but all American monkeys are not prehensile-tailed. 



By remembering these characters it is easy, with a little observa- 

 tion, to tell whether any strange monkey comes from America or from 

 the Old World. If it has bare seat-pads, or if when eating it fills its 

 mouth till its cheeks swell out like little bags, we may be sure it 

 comes from some part of Africa or Asia ; while, if it can curl up the 

 end of its tail so as to take hold of anything, it is certainly Ameri- 

 can. As all the tailed monkeys of the Old World have seat-pads (or 

 ischial callosities as they are called in scientific language), and as all 

 the American monkeys have tails, but no seat-pads, this is the most 

 constant external character by which to distinguish them ; and, having 

 done so, we can look for the other peculiarities of the American monk- 

 eys, especially the distance apart of the nostrils and their lateral po- 

 sition. 



The whole monkey-tribe is especially tropical, only a few kinds 

 being found in the warmer parts of the temperate zone. One inhabits 

 the Rock of Gibraltar, and there is one very like it in Japan, and these 

 are the two monkeys which live farthest from the equator. In the 



