[74 ALLEN S NATURALISTS LIBRARY. 



section, the Sakis (Pithecia). Their various species are re- 

 stricted to the great equatorial forests of South America. 



THE UAKARf MONKEYS. GENUS BRACHYURUS. 

 Brachyurus, Spix, Sim. etVespert. Bras., p. n (1823); W. A. 



Forbes, P. Z. S., 1880, p. 644. 

 Ouakaria, Gray, P. Z. S., 1849, p. 9. 



The species of this genus are at once recognised by their 

 short tail, being the only American Monkeys in which this 

 organ is short. The fur is short and silky ; the face short, and 

 often brightly coloured. The mammae are situated on the 

 breast. In the skull the lower jaw is dilated behind, and 

 certain bones, the parietal and the malar, are in contact with 

 each other for a more or less considerable extent on the side 

 walls of the skull. (Cf. W. A. Forbes, P. Z. S., 1880, p. 639, 

 figs. 5 and 6.) Tn Old World Monkeys this contact never 

 (except slightly in Hylobates) takes place. This is a useful 

 mark for discriminating between the skulls of New and Old 

 World Monkeys. (Forbes.') The shortness of the tail is due, 

 not to a reduction in the number of the vertebrae, which may be 

 15 to 17, but in their size. 



In the brain the cerebrum exhibits the more important 

 grooves characterising the brain of the higher Apes (Simiida) 

 well developed ; the cerebellum (or hind brain) is also well 

 developed. Thus in its general characters the brain of the 

 Uakaris approaches most nearly to that of the genera Cebus 

 and Pithecia (next to be described). By reason of its greater 

 complication and development, it departs widely from that of 

 the Titis (Callithrix) and the Squirrel-Monkeys (Chrysothrix). 



A relationship to the Howlers (Mycetes), suggested by the 

 external appearance of the Uakaris and the form of their lower 



