178 ALLEN'S NATURALIST'S LIBRARY. 



Ouakaria calva, Gray, Cat. Monkeys Brit. Mus., p. 62 (1870). 

 Pithecia calva, Schl., Mus. Pays Bas, vii., p. 228 (1876). 

 Pithecia alba, Schl., t. c. p. 229. 



(Plate XVI.) 



Characters. Fur very long, straight, and shining from neck to 

 tail. Face scarlet ; top of head nearly bald, greyish, passing into 

 brown anteriorly and at the sides, with bushy sandy whiskers 

 meeting below the chin ; throat dark brown, mixed with numerous 

 black hairs, the general tint being rich chestnut-brown ; back 

 whitish-grey, with black hairs mixed with white ones, which are 

 in greater number. Under surface fulvous brown, darker on the 

 breast, where brown hairs are numerous ; the same brown 

 tinge is visible on the arms, legs, the hinder region of the 

 thighs, at the wrist, and ankle, and especially on the tail; eyes 

 reddish-yellow. Length, 18 inches. 



Some species are paler than the above description, being 

 pale sandy-white, slightly rufous below and on the inside of the 

 limbs. 



Caecum 10 inches long along its greater curvature, and not 

 sacculated. 



According to Mr. Beddard, B. calvus zind B. rubicundus 

 agree very closely in external and in internal characters, while 

 B. melanocephalus differs more in external characters from the 

 other two than they do from each other. 



Distribution. Opposite Fonteboa ; banks of the Japura river 

 west of its mouth. This species appears to be confined to the 

 triangle formed by the union of the Japura river and the 

 Amazon. It does not pass east of Ega, nor does it cross to the 

 south of the Amazon, but keeps to the forests of the low lands 

 to the north of that boundary and south of the Japura. 



