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APES, MONKEYS, AND LEMURS 



THE HOWUNG MONKEYS 

 Genus Mycetes 



The howling monkeys, or howlers, derive their name from their vociferous 

 cries, which are sufficient in the living condition to distinguish them from all the 

 other American monkeys. To produce this extraordinary noise, of which more 

 anon, there is a peculiar hollow shell of bone joining on to the upper part of the 

 windpipe, corresponding to the so-called hyoid bone of man, which is a very small 

 and solid structure. The resonance of the voice within this cavity communicates to 



the cry its peculiar intensity. In order to 

 provide space for this bony shell, the sides of 

 the lower jawbone are extremely deep, and 

 by this characteristic, as well as by the extreme 

 flatness of the part containing the brain, the 

 peculiar skull may always be recognized. A 

 front view of the head of a howler is given 

 in the accompanying cut, to illustrate the form 

 of the nostrils in the American monkeys. 



The howlers differ from the two preceding 

 groups, and agree with the spider-monkeys 

 and their allies, in having prehensile tails, of 

 which the under surface of the extremity is 

 naked. In addition to the presence of the 

 large bony swelling at the top of the wind- 

 pipe, they may be at once distinguished from 

 all other prehensile-tailed monkeys by the ex- 

 treme obliquity of the plane of the face and 

 the projecting muzzle. This obliquity of the 

 face is connected with the flattening of the 

 hinder part of the skull, already referred to ; 

 and is so marked that the profile inclines back- 

 wards almost in a straight line from the muzzle 

 to the crown. Like all American monkeys, 

 except the spider-monkeys and some of their allies, the howlers have well-developed 

 thumbs. Their face is naked, with the muzzle very projecting ; the naked parts 

 being surrounded by a fringe of long hair on the forehead, cheeks, and chin. On 

 the forehead this long hair may be directed either backwards or forwards, but that 

 of the whiskers and beard always hangs down. The hair of the body, although 

 shorter than that surrounding the face, is relatively long. 



The howlers are especially abundant in Brazil, but they also range into Central 

 America. They are represented by a considerable number of species, but since 

 these are chiefly distinguished from one another by the color of their hair, and there 

 is considerable individual and sexual variation in this respect, it is in some cases 



HEAD OF THE VERA CRUZ HOWIJNG 



MONKEY. 

 (From Sclater, Proc. Zool. Soc.) 



