32 



THE LOWER PRIMATES 



the rhinal fissure on the lateral aspect, and a sHght further protrusion down- 

 ward of the tip of the temporal lobe. No actual distinction of an occipital lobe 

 can be made upon the lateral surface although the markings on the mesial 



4^k^ , 



tf 



Courtesy, American Museum oj Natural History 



FIGS. 12 AND 13. HAND AND FOOT OF LEMUR POTTO. 

 Left. Palmar surface of liand showing rudimfntary development of index linger, palmar creases and 



opposable thumb. 

 Right. Plantar surface of foot showing rudimentary second toe and opposable hallux. 



surface show that this specialization of the neopallium has already begun to 

 make definite expansions toward the occipital pole of the hemisphere. 



On the orbital surface of the brain the two orbital concavities are fairly 

 well marked. This surface has a general obliquity outward, which increases 

 the prominence of this concavity and permits the orbital plane to pass over 

 into the frontal surface without sharp angulation in the region of transition. 

 The interorbital keels are well marked. The olfactory bulb is large and 

 detachable for a certain distance, although the olfactory tract is short and 

 not detachable. The latter shows its greatest development in its lateral roots 



