HO 11 'LIXG .VOXKE I 'S. 



183 



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 backwards 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 pro- 

 jecting; 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 clown. 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 colour of their hair, and 

 there is considerable individual and sexual 

 variation in this respect, it is in some cases 

 difficult to decide as to which variations we 

 ought to regard as indicating distinct species, 

 and which merely as local races. The food of 

 these monkeys is stated to consist entirely of 

 leaves. 



Humboldt says that, when travelling in 

 the neighbourhood of the Orinoco, the rising of 

 the sun was always heralded by the cries of 

 the howlers. Frequently this traveller and his 

 companion, Bonplaiid, observed troops of them 

 moving slowly in procession from tree to tree. 

 A male was always followed by a number of 

 females, several of the latter bearing their 

 young on their shoulders. The uniformity 

 with which they perform their movements is 

 described as being very remarkable. According 

 to the observations of Humboldt, as detailed 

 by one of his biographers, whenever the 

 branches of neighbouring trees do not touch 

 one another, the male, who leads the party, 

 suspends himself by the naked prehensile part 

 of his tail, and, letting fall the rest of his body, swings himself till in one of his 

 oscillations he reaches the neighbouring branch. The whole file performs the same 

 movements on the same spot. The Indians told the travellers that when these 

 monkeys filled the forests with their howling there was always one that chanted, 

 as leader of the chorus. During a long interval one solitary and strong voice 

 was generally distinguished, till its place was taken by another of a different pitch. 



Writing in relation to a specimen of one of these monkeys, brought to him 

 when travelling on the Lower Amazon, Mr. Bates observes that "the howlers 

 are the only kind of monkeys which the natives have not succeeded in taming. 

 They are often caught, but they do not survive captivity many weeks. The one 

 of which I am speaking (apparently a female of the black howler), was not quite 



HEAD OF THE VERA CRUZ HOWLING MONKEY. 



(From Sclater, Proc. Zool. Soc.) 



