QUADRUMANA. 67 



ascend very high for the purpose of lodging a bony drum, formed 

 by a vesicular inflation of the hyoid bone, which communicates with 

 the larynx, and gives to their voice astonishing power, and a most 

 frightful sound. Hence their name of Howling Monkeys. The pre- 

 hensile portion of the tail is naked beneath. 



There are several species, whose distinguishing characters are 

 not yet well ascertained, for the colour of the fur on which they are 

 established varies with the age and sex. 



Simia seniculus, Buff. Supp. VII, 25. (Red Howling Mon- 

 key.) It is often sent to us from the forests of Guiana, 

 where it lives in troops; size that of a large fox ; colour, a red- 

 dish chesnut, rather deeper at the head and tail. The Alloucitte 

 ourson [Stentor urshius, Geoff.), Humb. Obs. Zool. I. pi. SO, 

 must differ from it, although slightly ; but it would appear that 

 there are many others, some of which are brown or black, others 

 of a pale colour. In certain species this pale tint is peculiar to 

 the females.(l) 

 The Common Sapajous have the head flat, and the projection of the 

 muzzle very moderate facial angle 60. 



In some of them, the anterior thumbs are either totally, -or nearly 

 so, hidden under the skin, and the prehensile part of the tail naked 

 beneath. M. Geoff, has formed them into a genus by the name of 

 Ateles.(2) 



The first species, the Chamek, Ateles pentadactylus, Geoff., 



(1) Marcgrave, I'.raz. 226, speaks of a black Guariba, with brown hands, that 

 Spix thought he had found iu his Seniculus niger. Mem. de Munic, for 1813, p. 

 333. Mycetes rujimanus, Kuhl. 



Marcgrave, 227, speaks of another species, all black and bearded, fig. p. 228, 

 under the wrong n^vae. oi Exquima, which must have been, it is probable, the 

 Mycetes barhatus, Spix, pi. 32. The female, ib. pi. oo, is of a light yellowish 

 grey. The male must be the Mycetes niger of Kuhl and Prince Maximil. de Neu- 

 wied. The Caraia of d'Azzara, which is black ; breast and belly of a dark red ; 

 the female brownish ; may be referred to this species. 



Pr. Max. has Sinother Mycetes ursinus, which appears to be much browner than 

 the ursinus of M. Geoffroy, and to approximate nearer to the M. fusciis, or the M. 

 discolor of Spix, pi. 30 and 34. This latter rather appears to be the St. fuscus of 

 Geoffroy. 



The Stravo-coloured Mouatte, Stentor stramineus, Geoff, and the Myc. stramineus, 

 Spix, pi. 31, of a yellowish grey, appears from its cranium to be of a different 

 species, but it ma)' merely be the female of a preceding one. It is easily seen, 

 also, that if their characters are so uncertain, their synonymes must be much 

 more so. 



Add the St.Jlavicaudatus, Geoff, of a black brown, with a yellow streak on each 

 side of the tail. 



(2) Ann. du Museum, VII, 260, et seq. 



