124 ON THE UAKARI MONKEYS. 



As regards the species of this genus, there are three well-marked ones, 

 each inhabiting a distinct geographical area ; of each of these I have 

 seen skins and skulls. They may be arranged as follows : 



a. Facie nigra. 



1. BEACHYUEUS MELANOCEPHALTJS. (Plate VI.) 



Simia melanocepliala (Cacajao), Humboldt, Rec. pi. xxix. p. 317 (1811). 



Pithecia melanocephala, Geoffr. Ann. Mus. xix. p. 117 (1812). 



Brachyurus ouakary, Spix, Sim. et Vesp. Bras. p. 12, pi. viii. (1823). 



OuaTcaria spixii, Gray, P. Z. S. 1849, p. 10, fig. 



Ouakaria melanocephala, Gray, Cat. Monkeys &c. p. 62 (1870). 



Pithecia melanocephala, Schlegel, Mus. P.-B. vii. p. 227 (1876). 



Ater, dorso lateribusque cum brachiis posticis plus minusve castaneo- 

 brunneis. 



Hob. Forests traversed by the Casiquiare and Rio Negro (Humboldt) ; 

 forests between the Solimoes and lea (Spix} ; Marabitanas, Rio Negro, 

 and Moura, Rio Branco (Natter er, fide Pelzeln apud Schlegel, I. c.). 



This species is at once distinguishable by its black face, as well as by 

 the black hands, feet, &c. It is the most northern form of the three, and 

 apparently the most wide-spreading also. No doubt it is the " black- 

 faced, grey-haired " species heard of, but not obtained, by Mr. Bates as 

 being found " 180 miles from the mouth of the Japura " (Nat. Amaz. ii. 

 p. 313). 



Of this species we have, at different times, had two specimens living 



P.Z.S. 1880, in the Gardens (vide Sclater, P. Z. S. 1870, p. 1). From the first of 



p. 646. these the water-colour drawing by Richter in the Society's possession, 



which is here reproduced on a diminished scale (Plate VI.), was 



taken. In all probability it is the skin and skeleton of this individual 



which are now preserved in the British Museum. [The stuffed skin is 



marked " Zool. Soc.'s collection," the skeleton 806 &.] 



b. Facie rubra. 



2. BRACHYTJEUS CALYUS. 



Brachyurus calvus, Isid. Geoffr. C. R. xxiv. p. 576 (1847), et Arch. 

 Mus. v. p. 560 ; Exped. Arner. Sud, Mammif. p. 17, pi. 4. fig. 1 (1855). 

 Oualcaria calvus (sic), Gray, P. Z. S. 1849, p. 10. 



pointed out to me that the same term also had been proposed some years previously to 

 Spix by Fischer (' Zoognosia.' i. p. 24) for a genus of Eodentia (1813). As, however, 

 this name has never, I believe, been adopted for use in that group, it seems to me quite 

 unnecessary, on that ground, to reject the name for the TJakaris. Purists will have, I 

 suppose, to adopt Lesson's barbarous term, proposed as a subgenus, Cacajao (Species 

 des Mammiferes, p. 181, 1840). 



