THE SPIDER-MONKEYS. 227 



based upon the development of the anterior thumbs, this mem- 

 ber being absent in B. arachnoides, replaced by a small nail- 

 less tubercle in B. tuberifer, and surmounted by a nail in B, 

 heinidactylus. In the " Magazin " of Messrs. Verreaux, in Paris, 

 I found specimens having upon one hand the tubercle, and upon 

 the other the nailed thumb, others with the tubercle on one 

 hand, but absent upon the other. St. Hilaire himself, in his 

 " Catalogue of the Primates," expresses a doubt as to whether 

 B. arachnoides and B. hemidactylus are really distinct. In 

 September and October, 1860, I was unable to find B. hemi- 

 dactylus in the Paris Museum, all the Brachytdes being labelled 

 Eriodes arachnoides." 



Distribution. Confined to the wooded region of the south- 

 east of Brazil. 



Habits. Arboreal, diurnal, and (it is supposed) gregarious, 

 frequenting the high forest trees, and subsisting on fruits. 



THE SPIDER-MONKEYS. GENUS ATELES. 

 Ateles, Geoffr., Ann. Mus., vii., p. 262 (1806). 



This is the fourth remaining genus of the Ceding the last 

 Sub-family of the Cebida. With the description of the Spider- 

 Monkeys, therefore, we shall have passed in review all the 

 species of the New World Platyrrhine section of the Anthro- 

 poidea. The species of this group derive their trivial name from 

 their long and slender limbs ; the name applied to them, how 

 ever, in their native forests by the Indians of Brazil is "Coaita." 

 They are characterised by their light and slender body, which 

 is narrower across the loins than across the chest. The head 

 is rounded, the forehead salient, and the muzzle somewhat pro- 

 jecting. Both pairs of limbs are much elongated, the hind- 



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