ORDER QUADRUMANA. 225 



The Yarke, (Simla Pithecia, ~L.) Buff. XV. xn. 



Blackish, circumference of the face white. 



The Black Saki, (Simia Satanas, Ho ff manse gg.} Humb. 

 Zool. Obs. L. xxvik 



Altogether black. 



The Red-Bellied Saki, or Night Monkey, {Pithecia rufi- 

 ventfis, Geoff.) Buff. Suppl. VII. xxxi. 



Brown with red belly. 

 There are a few of these whose tail is remarkably 

 slender. All come from Guiana or Brazil. 



THE OUISTITIS, 



(Hapales. Illiger. Arctopithecus^ Geoff.) 

 A small genus like the Sakis, and for a long time 

 confounded with them. They have in fact, like 

 the American monkeys in general, a round head, 

 flat face, lateral nostrils, having buttocks and no 

 cheek-pouches, and, like the Sakis in particular, 

 no prehensile tail. But they have only twenty 

 cheek teeth, like the monkeys of the old conti- 

 nent. All their nails are compressed and pointed 

 except -those of the hinder thumbs, and the fore- 

 thumbs are separated so triflingly from the other 



M. Geoffroy gives to his callitrix, to the aotus and pithecia the 

 common name of geopithecus. M. De Humboldt has given, Obs. 

 Zool. I. the figure of a very singular quadrumanum which he calls 

 the night monkey (Aotus. Illig.) but I cannot fix his place, not 

 having seen the cranium or teeth. 



