PARIETAL REGION IN THE PRIMATE BRAIN 319 



atives, areas 39 and 40, and the mental status of these individ- 

 uals is quite in harmony with the general results of anatomical 

 investigation. 



In Cercopithecus and indeed in Hylobates and Simla also, the 

 regio parietalis (areas 5 and 7 and the derivatives of the latter, 

 39 and 40) is quite small as compared with the regio occipitalis 

 (areas 17, 18 and 19 and the derivatives of the last) and is repre- 

 sented by a narrow band of cortex interposed between the oc- 

 cipital and temporal regions behind and the postcentral region in 

 front. In the discussion which follows we shall have occasion 

 to make use of the findings of Brodmann, Mauss and others and 

 if we seem to allow ourselves some latitude in the application of 

 these findings it is to bring them into line with other researches 

 and for the additional reason that they represent only single, 

 isolated cases in which the role played by individual variations 

 in the relative extent of various areas and in the fissural pattern 

 is difficult or impossible to determine and hence these charts 

 cannot claim the significance they might, were they based on the 

 examination of a large series of brains. The diagrams of Brod- 

 mann ('08) representing the various areas in Cercopithecus and 

 in Homo and those of Mauss ('11) in Cercopithecus, Hylobates and 

 Simla, although based on different principles, present a striking 

 correspondence and will be of great value for the understanding 

 of what is to follow. Two differences between these writers may 

 be noted as regards the brain of Cercopithecus; while the combined 

 areas 18 and 19 occupy about the same extent of cortex, the area 

 18 is in Brodmann's charts much more extensive than those of 

 Mauss. But a much more important discrepancy is found in 

 the parietal region. According to Mauss the area praeparietalis, 

 type 5, makes up the entire region above the interparietal sulcus 

 and the area parietalis, type 7, does not extend beyond that fis- 

 sure. Brodmann, on the contrary, finds type 7 extending upward 

 beyond the interparietal, between 5 and 19, onto the mesial as- 

 pect of the hemisphere. On this point we shall follow Brodmann, 

 since he finds a corresponding interposition of area 7 between 5 

 and 19 in Hapale and Lemur and even in Carnivora (Cercoleptes). 



