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N. W. INGALLS 



in the length of the interparietal sulcus and, on account of the 

 greater reduction of 17 near the mesial border, to the character- 

 istic form of the lunate sulcus. This enlarged parietal area is 

 due to the expansion of area' 7, separating the upper and lower 

 parts of which we have the sulcus interparietalis proprius (ramus 

 horizontalis) . As has been already shown, this part of the in- 

 terparietal is very short in all forms below the Simiidae, forming 



Fig. 16 Cortical areas in man, after Brodmann ('08). 



merely a short connecting link between those portions of the in- 

 terparietal which will become the inferior postcentral and the 

 ramus occipitalis (paroccipital of Wilder). Referring to the ac- 

 count of interparietal in the Cercopithecidae, it will be remembered 

 that this sulcus apparently gave off a branch, but in reality was 

 itself continued upward, limiting the first annectant gyrus in 

 front. This furrow forms the posterior limit of area 7 and a small, 

 and doubtless varying extent of the ascending limb of the inter- 

 parietal immediately in front, in the region where it is crossed 

 by area 7, represents the sulcus interparietalis proprius. Its an- 



