THE HOWLING MONKEYS 



183 



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 traveling in the neighborhood of the Orinoco, the 

 rising of the sun was always heralded by the cries of the howlers. Frequently this 

 traveler and his companion, Bonpland, observed troops of them moving slowly in 



THE BLACK HOWLER. 

 (One-fifth natural size. ) 



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. Ac- 

 cording to the observations of Humboldt, as detailed by one of his biographers, 

 whenever the branches of neighboring trees do not touch one another, the male, who 

 heads the party, suspends himself by the naked prehensile part of his tail, and, let- 



