630 



E. H. J. SCHUSTER. 



hemisphere of Cevcopithecus agrees in the main very well 

 with Campbell's account summarised above. The slight 

 differences to be noted may be due to the gradual nature of 

 the transition between one type of cortex and its neighbours. 

 Thus Brodmann recognises four different types against 

 Campbell's two, namely, Nos. 8, 9, 12, and 2b. Of these, 

 No. 9 clearly corresponds with Campbell's frontal type, and 

 No. 12 with the prefrontal, though the extent of the area 

 occupied by No. 12 is relatively considerably less. 



No. 8 lies immediately in front of the sulcus arcuatus ; it 

 occupies a narrow strip of the lateral surface of the hemi- 

 sphere, bounded behind by type No. 6 and in front by type 

 No. 9. In structure it resembles the posterior portion of 

 Campbell's frontal area, being intei-mediate between the two 

 types, which it separates. No. 25 lies completely on the 

 mesial surface, where it occupies a comma-shaped area between 

 No. 9 (frontal area) and No. 24 (the nnterior limbic area). 

 Its structure is intermediate between these. 



Pariktal Occipital and Temporal Lobes. 



Post-central Type (fig. 6). 



^r:^^^l^^i^^^&y/t^ 



The post-central type of cortex is illustrated in fig. 6, 

 which is taken from tlie crown of the post-central gyrus a 

 little way below the anterior end of the sulcus post-cenM-alis 

 superior {jx-.s.). The cortex is here 1'7 mm. in depth, of which 

 the lamina zonalis (i) occupies the upper '1 mm. The lamina 

 granularis externa (ii), composed as usual of small pyramids 

 and granules, is fairly well developed, but not so closely 

 crowded with cells as to be sharply marked off from the under- 

 lying lamina pyramidalis; it reaches to a depth of about 

 •25 mm. The lamina pyramidalis (iii) is very distinctly sub- 

 divided into an upper stratum (iii (i) containing medium-sized 



