PARIETAL REGION IN THE PRIMATE BRAIN 329 



within area 7, in a sense axial, or they contribute to the fold- 

 ing in of areas 21 and 22 as they gradually take up a position lower 

 down on the hemisphere. It is not uncommon to find between the 

 superior temporal and lunate a large curved fissure parallel with 

 the latter, its upper end being formed by a long anterior occipital, 

 the lower by a fissure which is often represented by the descending 

 branch of the superior temporal, while the middle connecting 

 piece, probably formed mechanically as a continuation of either 

 of the others, is less constant. This furrow forms the anterior 

 limit of area 19, with the exception of its lower segments which cut 

 directly through this area; the significance of this will be noted 

 later. A part of area 21 is submerged in front. 



In this inferior parietal region other noteworthy features 

 are constantly encountered which are to be considered as fore- 

 casting its future subdivision in man. Above the posterior end 

 of the Sylvian and in front of the superior temporal there are 

 often found furrows indicative not only of an increase in area 

 but also of a suggested separation of area 7 into an anterior and 

 posterior portion such as occurs in man. In some cases, even in 

 Hylobates, there is a well defined offshoot from the interparietal 

 cutting more or less deeply into the surface between the Sylvian 

 and parallel sulci. Although by no means always present, it may 

 be very well marked or apparently represented by a long branch 

 from either of the two mentioned sulci or it may be independent. 

 It is, to be sure, an individual variation but suggestive of a cor- 

 tical development more nearly approximating the human condi- 

 tion the development of which is likewise an individual variation. 

 A comparison of this region in the human and anthropoid brains 

 makes it evident that we must seek in the latter the foreshadowing 

 of the supramarginal and angular areas (or gyri) of the former. 

 It is the typical development of this sulcus between these areas 

 which constitutes the sulcus intermedins primus of Eberstaller. 



The distribution of the preoccipital, or peristriate, area 19, on 

 the first annectant gyrus has already been mentioned and it is 

 essentially this condition which is preserved throughout the Pri- 

 mates. From this position, i.e., above the interparietal, Brod- 



