PARIETAL REGION IN THE PRIMATE BRAIN 



317 



many regions with the introduction of a gradually increasing 

 number of newer areas derived from the further differentiation 

 and subdivision of older ones. The cortical areas which have 

 suffered the most relative reduction are those in relation to the 

 special senses, although there is no intention to refer here to that 

 classical example of cerebral reduction, the rhinencephalon. The 

 motor and general sense areas, on the contrary, are remarkably 



superior postcentral 

 central \ 



interparietal 



parfeto-occipifal. 



lunate 



middle temporal 

 superior temporal 



Fig. 12 Cortical areas in Cercopithecus fuliginosus, after Mauss ('08), figure 

 2. In figures 12 to 17 inclusive, the same signs are used to denote the various areas, 

 but certain changes have been introduced in the signs used. For further explana- 

 tion see text. 



constant in their extent and fissural relations. It is further clear 

 that two very striking changes have taken place. Firstly, a very 

 marked reduction in the extent of the area striata, type 17 of 

 Brodmann and Mauss, especially as regards its extension onto 

 the lateral aspect of the hemisphere, and a relative increase, as 

 compared with the area striata, of the parastriate and peristriate 

 areas (Elliot Smith), occipital and preoccipital areas or types 18 

 and 19 of Brodmann and Mauss. Secondly there have become 



