CATARRHINES AND PLATYRRHINES 



in the continents of the old world. This is seen also 

 in the monkeys. The American monkeys have the 

 nostrils wide apart with a septum between them ; the 

 tail, when present, is often, indeed nearly always, 

 prehensile, and serves the purpose, as it has been 

 termed, of a fifth hand, to enable its possessor to grasp 

 additionally on to the branch of a tree. It is not clear 

 that the monkeys of America are deafer than their allies 

 of Asia and Africa ; but it is an anatomical fact that 

 the former have not the little spout-like bone for con- 

 veying sound to the internal part of the ear devoted 

 to the reception and analysis of sound waves, which is 

 present in the Catarrhines. The visitor to the Zoo 

 will note the eager way in which monkeys will often 

 cram nuts and other proffered food into their cheeks 

 to be disgorged later, and eaten at leisure ; but it will 

 be noted that no monkey hailing from the American 

 continent ever does this ; there are indeed in the 

 Platyrrhines no cheek pouches at all. Nor do those 

 gaudy red callosities, so characteristic of baboons and 

 other apes of the Old World, ever deck or adorn the 

 monkeys of America. 



The Platyrrhine apes of America consist of two main 

 groups, which are themselves further apart than are 

 any two forms among the apes of the Old World, not 

 excepting such apparent contrasts as the gorilla and 

 the bonnet monkey. In the tiny little marmosets the 

 tail is riot prehensile, and the hand is, so to speak, not 

 a hand but a paw. The thumb is not opposable to the 

 other fingers, and the nails upon those fingers are 

 rather claws than nails ; but these characteristics are 

 obviously so far not ape-like, and ally the marmosets 

 to animals lower in the series than apes. These points 

 can be readily verified by the visitor. 



The apes of the Old World are usually divided into two 

 great groups, the Catarrhines and the Simiidae, or an- 



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