PARIETAL REGION IN THE PRIMATE BRAIN 



321 



lying in front of the inferior postcentral below, but behind the 

 so-cfeUed superior postcentral above while an extension of 7 seems 

 to have taken up the position above the interparietal formerly 

 occupied by 5. It would appear, therefore, that the fissure which 

 is apparently so similar in the lower apes and the Simiidae and 

 known, in its entirety, as the interparietal, exhibits certain dif- 

 ferences in the two groups in that the various segments comprising 

 the sulcus differ relatively in the degree of their development. The 



Fig. 14 Cortical areas in Hylobates, after Mauss ('11). 

 are not shown. 



Certain small areas 



sulcus postcentraUs superior which is less constant in the lower 

 apes can hardly be looked upon as the same sulcus in higher forms. 

 While Mauss does not in his charts of Hylobates and Simla sub- 

 divide area 7, he states in the text that it is separated into an 

 upper and a lower portion, without however, indicating where the 

 dividing line would fall. Doubtless, as we shall see later, it would 

 correspond with the interparietal. It is often difficult or actually 

 impossible from the charts and sections of these writers to de- 

 termine the exact relation between many areas and fissures. To 



