516 PROCEEDINGS OF THE ACADEMY OF 



Caput pyramidale, manibus pentadactylis ; os hyoideum prominens, caver- 

 nosum. 



Head pyramidal, facial angle about 50, inferior maxillary large and massive, 

 incisors small and equal, canines, and molars large ; occipital bone with a well 

 denned median ridge terminating superiorly in an osseous tubercle ; body of 

 hyoid bone very large and hollow, very apparent in the living animal, chin 

 bearded, face naked. 



Of all genera of American Qnadrumana, the present is perhaps the most un- 

 attractive and even repulsive in appearance ; a huge pyramidal head placed 

 upon a thick unwieldy body, contrasts strongly with the globular heads and 

 comparatively light bodies of the genera before enumerated. Its chief pecu- 

 liarity, however, consists in the enormous development of the body of the hyoid 

 bone ; this is of an ovoid form and hollow ; one in the collection of the Academy 

 has a capacity of 5 cubic inches.* 



By means of this curious organ the voice of the animal is augmented to such 

 a degree that it may be heard at a distance of three miles. I have been in- 

 formed by persons residing at Panama, that the senicula loses its voice en- 

 tirely in captivity. The same may be true of other species. 



Aluatta seniccla, Lacepede. 



Simia seniculus, Linn., Ed. xiii. 1788, p. 36. 



Aluatta seniculus, LactpSde, Mem. de l'lnst., vol. iii. 1800, 1801, p. 489. 



Stentor seniculus, Geoff., Ann. du Mas., vol. xix. 1812. 



Stentor chrysurus, Is. Geoff., Mem. du Mus., vol. xvii. 1848, p. 166. 



Mvcetes laniger, etauratus, Gray, Ann. and Mag. of Nat. Hist., vol. xvi. 1S45, p. 



219, 220. 

 Aluatte, Duffon fy Audebcrt. 

 Aluatte, Onarine et Hurleur, LatreiUe. 

 TCoyal monkey, Pennant. 



Icones,Latreille, Les Singes, vol ii. T. 115 and 116. Audebert, fam. 5, sect. 1, 

 fig. 1. Guerin, Mag. de Zoologie, 1832, class 1, torn. vii. 



A. Corpore fulvo-fusco aut anrescente ; capite collo ante brachiis, femoribus 

 et cauda castaneis ; barba longa rufescente ; facie pectoreque, nudis et nigris. 



Hab. Brazil, Equador, Venezuela and New Grenada. 



Head, neck, limbs and tail, dark chestnut brown ; back and sides golden yel- 

 low ; beard in adult long, the hairs composing it being mostly golden yel- 

 low at their bases, and chestnut brown through the remainder of their length ; 

 face naked and black; chest naked, abdomen sparsely covered with long, 

 brownish hairs. 



The above description is taken from an adult male (No. 985) in the collection 

 of the Academy. The young have the same general distribution of colors, 

 though of a darker shade. Dr. Gray, in his paper upon the genus Mycetes, 

 (Ann. and Mag. Nat. Hist., Oct. 1845, p. 219) lays great stress upon the texture 

 of the hairs as a specific distinction. In the present species the hairs of the 

 adult are soft to the touch, while those of the young are hard and rigid. In 

 regard to the identity of this species with the chrysurus of Isidore Geoffroy, I 

 was for some time in doubt, but the examination of a large number of speci- 

 mens has convinced me that it is but a slight variety of the senicula ; the 

 skulls present no dissimilarity ; the only external difference being that the api- 

 cal third of the tail is similar in coloration to the back. In a suite of speci- 

 mens from New Grenada, one has the terminal portion of the tail bright golden 

 yellow ; in the second, it is somewhat darker, and in the remaining two it has 



* A full and complete account of the anatomy of this curious organ and the adjacent parts may 

 be found iu the Oeuvres de Pierre Camper, Paris, 1803, 3 vols. 12mo., vol.1, p. 70. Also in the His- 

 t .ire Naturelledes Singes, Latreille, Paris, 1801, 2 vols., 12mo. vol. 2. p. 125. 



[Nov. 



