10 



crown with short hair ; the chin scarcely bearded ; the lower cutting 

 teeth very much shelving ; legs elongate. 



This genus forms part of the genus Brachyurus of Spix ; and if 

 SpLx had not evidently described the teeth, &c. of his first species in 

 his generic character, I should have been induced to have retained for 

 this group the name of Brachyurus, which is more applicable to it 

 than to the one to which it is apphed ; and indeed M. Isidore Geof- 

 frey appears to have so applied it. 



Several species have been described which chiefly differ in the length 

 of the tail ; as, 1 . Ouakaria Spixii ; Brachyurus Ouakari, Spix, 

 Brazil, t. 8, with the tail about one-third the length of the body. 

 2. Ouakaria calms; Brachyurus calvus, I. Geoff. Rev. Cuvier. 1847, 

 137, much paler in colour, but it is very doubtful if the shortness of 

 the tail does not depend on the imperfection of the specimen, and the 

 colour on partial albinism. 



We have specimens of B. calvus in the British Museum, presented 

 by M. Bourcier. The skull may be thus described : — 



The cutting teeth projecting; 

 the upper one broad, especially 

 the two middle ones ; lower one 

 elongate, narrow, more sloping, 

 and projecting like those of Indri. 

 Canines conical, far away from 

 the cuttmg teeth, leaving a large 

 vacancy ; flattened in front ; they 

 are flattened before and behind, 

 placed rather obliquely, with a 

 sharp inner edge. The skull is 

 very unlike that of the Cebidce ; 

 most allied to that of Pithecia 

 /eucocephala,hnt the cutting teeth 

 in that species are not so proclined. 



The converging, slender, shehang, cutting teeth in the lower jaw 

 of this genus, as well as its slender limbs and the shortness of its tail, 

 bear a certain resemblance to the Indri amongst the LenmridcB. 



The form of the lower jaw also offers a good character for the 

 distinction of the genera. 



1. Lower jaw not dilated behind. 



Atelina (part). 



Ateles. 

 Cebina. 



Cebus. 

 Pitheciana (part). 



Pithecia. 

 Jacchina. 



Jacchus. 



Midas. 



2. Lower jaw dilated behind. 



Mycetina. 



Mycetes (much). 



Lagothrix (moderately). 

 Atelina (part). 



Brachyteles (moderately) . 

 Callitrichina. 



Callithrix. 



Chrysothrix. 



Nyctipithecus. 

 Pitheciana (part). 



Brachyurus. Ouakaria. 



