CHARACTERS OF THE SOUTH AMERICAN MONKEYS. 103 



Both in Alouatta and Lagothrix fhe pollex is normally developed 

 for the family, being perhaps a little shoi-ter relatively than in 

 Gebus but longer than in Gacajao. The hallux is also of normal 

 length and strength*. (Text-fig. 6, C, D, and text-fig. 7, A, B.) 



In Ateles, as is well known, the hand differs from that of other 

 genera of Oebidse, except Brachyteles, in having the pollex func- 

 tionless and at most forming a small excrescence on the side of 

 the palm ; and it is noticeable that digits 2, 3, 4, and 5 are evenly 

 spaced as in Cebios, CaUicehus, etc., and that there is no grasping 

 space between digits 2 and 3 as there is in Alouatta and Lago- 

 thrix. The hand of Ateles is therefore not derivable from the 

 type of hand seen in Lagothinx, but from the more primitive type 

 of hand seen in Cebus for example t. (Text-fig. 8, A, B.) 



Text-fiffure 8. 



A. Right hand of Ateles paniscus, from below. 



B. fiight foot of the same. 



The foot of Ateles is chai^acterised by the reduction in the size 

 of the hallux, which is both shorter and weaker th;in in other 

 genera, the big muscular lobe at the base, representing the 

 " ball" of the human thumb, being scarcely vlsibl}'' developed. 



* In a specimen of L. irifumdtus the second and third digits of the foot were 

 united hasally bj' a short web. Possibly this was au abnormality, since no such 

 variation occurred in an example of L. lagotricha, 



■\ The onlj' genus of Monkeys which resembles Ateles [and J3raeliyteles] in the 

 suppression of the pollex is the Catarhine Colohus. In the latter, however, the 

 suppression of the pollex is clearb' foreshadowed in FitJiecus ( = Fresbytes = Senino- 

 'pitheeus), where it is greatly reduced. 



