CHAP. IV] THE GENERAL ANATOMY OF GORILLA 



193 



of the areas. Some sulci undoubtedly mark the boundaries of par- 

 ticular neo-pallial areas. And even though the precision and con- 

 stancy of this relation be open to question, the general statement 

 still holds good. On such grounds the significance of such furrows 

 is greatly enhanced. Finally, the association areas, regarded in 

 the light of their history, their disposition and their extent provide 

 the best material basis so far known for the physical assessment 

 of psychical differences between the ape and the human being. 



The following notes provide an account of some details of the 

 cerebral anatomy of the Gorilla. 



Infrapariefal sulcus 



Central sulcus 



Sulcus lunahjs 



Inferior occipital Sulcus 



Ant. limiting 

 •Sulcus of Reil 

 (fronto-orbita!) 



Sup-limiting 

 Insula \ sulcusofReil 



Olf.n. 



Parallel sulcus 



Fissure of Sylvius 

 (post.limb) 



Fig. 127. Lateral aspect of the right cerebral hemisphere of a young Gorilla 

 (Simiidae) The olfactory nerves are attenuated in point of size : the cerebral 

 surface is much more convoluted than in the preceding examples and recalls the 

 appearance of the human cerebrum. (Mus. Anat. Cant. Cr.) 



When compared with the other large anthropoid apes, the Gorilla is seen 

 to stand in a position nearer to Man than these. The cerebrum is ovoid, and 

 strongly rostrated anteriorly, the frontal lobes being deeply excavated in- 

 feriorly by the upward projection of the orbital plates of the frontal bone. 

 The frontal lobes are thus less full and rounded, both absolutely and propor- 

 tionately, than those of Man. The occipital end of the hemisphere does not 

 overlap the cerebellum to the same extent as in Man, and the cerebrum is 

 smaller in proportion to the cerebellum than in the human brain. 



The following notes are bssed upon Professor Elliot Smith's description 

 of the brain of a Gorilla in the Museum of the Royal College of Surgeons. 

 At the base of the brain the posterior rhinal fissure is retained with 

 diagrammatic clearness, and thus demarcates the neo-pallium from the 

 pyriform lobe. There is a deep vallecula Sylvii, which leads into the stem 

 of the Sylvian fissure. The latter is formed by the meeting of temporal 



i>. m. 13 



