Thompson, Cells in the Cerebral Cortex of Man. 1 1 9 



Region 10. The lateral surface of the occipital lobe. 



Region 11. The mesial surface of the occipital lobe. 



Region 12. The first temporal gyrus. 



Region 13. All the temporal lobe except the first gyrus. 



Region 14. The hippocampal gyrus (omitted).^ 



Region 15. The gyrus fornicatus and the portion of the 

 first frontal gyrus bordering immediately upon it. 



Region 16. The Island. 



Fio. I FiG. II. 



Explanation of Figs. I and II. 



The accompanying Figures I and II show by the corresponding numerals 

 the regions selected by Hammarberg and enumerated above. By the heavy 

 broken lines the several lobes, frontal, parietal, occipital and temporal, are 

 marked off from one another. 



Figure I. — Lateral aspect. Figure II. — Mesal aspect. 



D. In all these regions, Hammarberg reduces the corte x 

 to a six layer arrangement which he regards as typical. Any 

 departure from this he represents either as fusion of two layers, 

 or as subdivision of one or more layer or layers. Thus the 

 cortex of region 5 appears to be a four layer cortex, because 

 layers two and three are fused, and layer four is so much re- 

 duced that it is scarcely recognizable as a separate layer. Ham- 

 marberg's first four layers are identical with Meynert's first four 

 as quoted by Quain.^ But between Meynert's fourth layer, 

 composed of small irregular shaped cells, and his fifth layer, 

 made up of fusiform cells, Hammarberg finds a layer of pyramidal 

 cells which he calls the ganglion cell layer. The last layer, his 



' The data for the hippocampal gyrus were very incomplete, and since the 

 region contains so few cells at any rate, it has been omitted in making the 

 calculations. 



' Elements of Anatomy. Tenth Edition. Vol. Ill, Pt. i, p. 167 ff. 



