MAMMALIA. 749 



dactylous, with pollex distinct, somewhat short, little separate from 



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the other fingers. Molar teeth ^ ^ , with four obtuse tubercles. 



b b 



Nostrils severed by a broad septum, patulous laterally. 



These monkeys (the genus Cebus ERXL.) are, like the preceding, 

 exclusively proper to America. From the form and position of 

 their nostrils, GEOFFROY gave them the name of Platyrhini. The 

 anterior limbs have a thumb only slightly distinct from the other 

 fingers, whence OGILBY proposes to name these monkeys pedimana 1 . 

 All of them have a tail, but, like the preceding division, have no 

 buccal pouches, which occur in the monkeys of the old world 

 alone. They are on the whole small in comparison with the 

 monkeys of the old world, and have small molars 2 . 



t Tail lax, vittous, not prehensile. 



Pithecia DESM., ILLIG. Incisor teeth somewhat prominent 

 obliquely, the lower long, canines large, thick, conic, molars 

 small. Tail very villous. 



a) Tail long, equalling body. Sp. Pithecia leucocephala AUDEB., Simia 

 pithecia L., Pithecia chrysocephala Ism. GEOFFR., BUFF. xv. PI. 12 (cop. 

 in SCHREB. Sdugth. Tab. 32), Archives du Mus. v. PI. 29; the young 

 animal has the points of the hair yellow; it is the Pithecia ruftventer 

 GEOFFR., BUFF. Suppl. vn. PL 30, 31, GUER. Iconogr., Mammif. PI. 4, 

 fig. 3, Guiana; Pithecia hirsuta SPIX (and P. inusta ejusd ) Brasil; 

 Pithecia satanas HOFFMANN SEGG, Cuv. R. Ani., e<L. ill, Mammif. PL 18, 

 fig. i. 



b) Tail much shorter than body (Brachyurus SPIX in part). Sp. Pithecia 

 melanocephala, Simia melanocephala, HUMB. Recueil d'Observ. de Zool. I. 

 PL 29. 



Nyctipithecus SPIX, (Nocthora F. Cuv., Aotus ILLIG.). Two 

 middle upper incisors broad, lower obliquely procumbent ; canines 

 moderate. Eyes large. Ears partly hidden amongst the hair of 

 head. Hind feet longer than fore feet. Tail longer than body. 

 (Orbits very large. Zygomatic bones inflated behind the orbits.) 



1 Observations on the opposable power of the thumb, considered as a zoological charac- 

 ter, LOUDON'S Magazine of Nat. Hist. i. 1837, p. 49 seq. 



2 Figures of the skulls of Lagothrix, Pithecia, Chrysothrix and Callithrix have 

 been given by WAGNEB in Abh, der Munchn. Akadem., mathem. physik. Klasse n. 

 Tab. ii. s. 516. 



