508 PROCEEDINGS OF THE ACADEMY OP 



same name having been given to a genus of birds by Vieillot, (Oiseaux de 

 L'Amerique septentrionale, p. 52, 1807,) five years previous to its being applied 

 to the above mentioned ape by Geoffroy St. Hilaire ; and, on page 53 of the 

 same work, the specific name niger is retained for a howler, the female and 

 young of which are characterized as being yellowish (jaunatre.) The third rule 

 is not generally recognized at the present day. 



The measurements recorded have been taken with great care, but allowance 

 must be made for the distortion of the specimens by skinning and mounting ; this 

 distortion is sometimes very great, especially in the specimens from the Para- 

 guay and Atrato expeditions. The length of tail in the same species is very 

 variable, owing probably to the great liability of that organ to injury. 



The materials for the present paper have been drawn from the following 

 sources. The collection of the Academy of Natural Sciences of Philadelphia ; 

 that of the Smithsonian Institution, Washington City, the Quadrumana belong- 

 ing to which, collected by the United States' Paraguay, Amazon, and Atrato Ex- 

 peditions, were kindly forwarded to me by the Secretaries, who are ever ready 

 to assist the student-naturalist by every means in their power; the magnifi- 

 cent collection of the British Museum, London, opened to me without restric- 

 tion, through the kindness of Dr. J. E. Gray, and Mr. G. R. Waterhouse ; the 

 collection in the magazin of Messrs. J. & E. Verreaux, No. 9, Place Royale, 

 Paris, where every facility for investigation was kindly afforded me ; and a view 

 (through the glasses,) of the specimens in the Musee d Histoire Naturelle, at the 

 Jar din des Plantes, Paris, where, however, I was refused permission to open the 

 cases for the closer examination of the specimens. lam therefore unable to 

 give measurements of some species, unique specimens of which are preserved in 

 that magnificent, though inaccessible collection. 



I adopt the following classification of the American Quadrumana : 



Order QUADRUMANA. 



4 

 Family Simiid^e. Dentes primores - contigui. 



4 

 6 

 Subfamily Cebinae. Molares - 



6 

 5 

 Subfamily Hapalinae. Molares - 



5 



The CebincB I propose to divide into three tribes, viz.: 



Lagothrice. Cauda prehensili ; apice subtus calva ; dente3 primores 

 erecti. 



Cebi. Cauda laxa; villosa ; dentes primores erecti. 

 Pitheciae. Cauda laxa; villosa; dentes primores obliqui. 



The Cebira have been regarded by most authors as having the prehensile tail, 

 and this is mentioned by Erxleben (Syst. 1777, p. 44,) as a generic character of 

 this group. Though sufficiently flexible to be wound around the body, it is far 

 from serving the purpose of a fifth band, as is the case in the Lagothrices. This 

 organ in the Cebi is clothed with hair to the tip, while in the Lagothricines the 

 terminal inferior portion is naked and callous. 



Tribe I. LAGOTHRICES. 



Simia (parte), Linn., Ed. xiii. 1788, p. 26. 



Cebus (parte), Erxleben, Systema, 1777, p. 44. 



Gymnuri, Sjjix, Sim. et Vesp., 1823, p. 1. 



Cebus (parte), Fisher, Syn. Mam., 1829, p. 37. 



Atelina and Mycetina, Gray, Proc. Zool. Soc, 1849, p. 10. 



Cauda longa, prehensili ; aoice subtus calva. 



[Nov. 



