CORTICAL CELL LAMIXATIOX OF PAPIO HAMADllYAS. 685 



intra-parietalis, and invests the triangular area lyiug between 

 that fissure and the upper end of the sulcus temporalis 

 superior; below this it extends forwards and downwards on 

 the upper side of the Sylvian fissure; it gradually becomes 

 narrower, and finally dies away a little in front of the lower 

 end of the sulcus centralis. 



The inferior parietal cortex corresponds in position and 

 structure to Brodmann's type 7. That part of it; which lies 

 ill the mesial surface and on the lateral surface above the 

 intra-parietal corresponds with Campbell's parietal area, but 

 is notably less in extent than in the liigher npes or in man. 

 The remaining area is according to Campbell clothed with 

 temporal cortex, but there is so great a similarity between 

 the two types that there is no great antagonism in the two 

 descriptions. 



Calcarine Type (fig. 9). 



V V VVVVVV WW 

 ^V V WVVVWvV 



^ vvv wvvvvvv 



V vvv w>/vvf y 



V VVV«/VVVVW V V 



The calcarine type of cortex is illustrated in Hg. 9, a draw- 

 ing taken from the wall of the lower branch of the posterior 

 bifurcation of the calcarine fissure. Here the cortex is just 

 over I'o mm. in breadth. 



The lamina zonalis occupies rather more than the upper 

 ■1 mm. of this, and the lamina granulans externa forms a 

 narrow border of small pyramids and granules below it. The 

 lamina pyramidalis, consisting of small- and medium-sized 

 pyi'amids, extends to a depth of "4 mm. It is densely crowded 

 with cells, which follow the usual arrangement m being larger 

 near the lower border. The largest of them do not appear to 

 exceed a length of 25 fx. What is considered by Brodmann to 

 be homologous with the lamina granularis interna occupies 

 about half the total breadth of the cortex, extending, as it 

 does, from a depth of *4 to a depth of 1'15 mm. It can be 

 divided into three strata : (1) An upper layer of granides 



