70 



ARBOREAL MAN 



the thumb is rudimentary or absent, while the Woolly 

 Monkeys {Lagothrix) possess a thumb. The Capuchins of 

 the typical genus Cebus possess a well-developed thumb 

 and a tail, which, though partially prehensile, is not so 

 specialized as that of Ateles or Lagothrix. 



Fig. 24. 



Fig. 25. 



Pig. 24. — Plantar Surface op the Eight Foot of Tarsius 

 Spectrum, showing the Peculiar Development of the 

 Big Toe. 



Pig 25. — Palmar Surface of the Eight Hand of Tarsius 

 Spectrum. 



In all the Old- World Primates the pollex, when present, 

 is opposable. In the Lemurs the big toe is opposable 

 and is often extremely specialized, the hallux standing 

 apart from the foot in some species, such as Tarsius 

 spectrum, in a manner reminiscent of the split foot of 

 some of the arboreal members of lower orders (Fig. 24). 

 The thumb is also well developed and opposable in most 

 higher or typical Lemurs (see Fig. 25). In the Asiatic 



