12 ZOOLOGY OF THE VOYAGE OF THE SULPHUR. 



bably the middle age ; and P. inusta, of the same author, as the young of this 

 species. 



These examples may be considered as a fair specimen of the gratuitous 

 assumption and careless compilation of this author, whose work is put forth as 

 the commencement of a new Species of Mammalia.* 



This short sketch of what has hitherto been done, shews that naturalists 

 have had considerable difficulty in distinguishing the species of this genus which 

 have already been described. 



We have several specimens of the genus in the British Museum collection, 

 and they very naturally arrange themselves into three very easily characterized 

 species, but, at the same time, though I have not observed any other species in 

 any of the Continental collections, I find it very difficult to apply to two of them 

 with certainty any of the descriptions and figures of the authors before referred 

 to ; and therefore I have thought it best, for the purpose of more distinctly 

 characterising the species brought home by Capt. Sir Edward Belcher, to de- 

 scribe the three species and figure those parts of them which furnish the most 

 distinctive characters. 



The black Yarke. — Pithecia leucocephala. 



Plate II. — Head. 



Simia leucocephala, Audeb. Sing. vi. l.f. 2. (not good.) 



Simia rithccia, Schreb. t. 32, from Buffon, and Shaw, Lever. Mus. iv. t. 1C9. (wood.) 



Pithecia leucocephala, Geoff. Ann. Mus. xix. 117. ; Kuhl, Beitr. 45. 



ochrocephala, Kuhl, Beitr. 41.. 



inusta, Spic, Braz. 15. t. 10.? (var. hands pale). 



Saki, Buffon, II. N. xv. t. 12. 



The head covered with hair. The front half of the head, forehead, sides of the face and 

 cheeks, covered with short yellow hairs, the lips with short white bristly hair. The nose, 

 and a narrow streak up the centre of the forehead nearly naked, blackish. Hair of the 

 back of the head short, black ; of the rest of the body, limbs and tail, very long and 

 straight, uniform brownish black ; of the hands, short and black. 



Inhab. Tropical America. 



This species, which appears to have been longest known, is easily distinguished 

 from the other two by the uniform colour of the hair on the head, and the peculiar 



* Mastologie Methodique, Species des Manimiferes Bimancs et Quadrumanes. Par M. R. P. Lesson, &c. 

 Paris, 1840. Svo. 



