MYCETES SENICULUS 201 



only demonstrable advance in man. It is in reality an advance due to the 

 brain acting with increased delicacy, bringing in its train the functions which 

 distinguish human mental faculty from that of all other animals. 



CoUTte&y, American Museum oj Natural History 



FIGS. 107 AND 108. HAND AND FOOT OF SPIDER MONKEY. 



Left. Dorsum of hand, showing well-developed fingers and finger-nails, absence of the thumb. 



Right. Dorsum of the foot showing long metatarsus, long toes, opposable hallux, well marked toe-nails. 



Brain Measurements and Indices in Mycetes Seniculus 



Diameters of the skull 



Occipito-nasal -8 mm. 



Bitemporal 42 mm. 



Length of the brain case 56 mm. 



Brain, includmg cerebellum and brain stem 



Longitudinal 52 mm. 



Transverse 40 mm. 



