634 E. H. J, SOHITSTEE. 



much smaller than those at iii h, but scattered among them 

 are a few of outstanding size, yet not so large as the corres- 

 ponding cells of the post-central or superior parietal regions. 

 The lamina multiformis may be divided into an upper lamina 

 triangularis and a lower lamina fusiformis. The cells of the 

 former are large and numerous with broad triangular or 

 (]uadrilateral forms predominating, while those of the latter 

 are smaller and slenderer, and many of them approach the 

 fusiform in shape. On the mesial surface the breadth of the 

 cortex is about 4- mm. less. In this reduction, which is 

 associated with the more tangential arrangement of the fibres 

 in the underlying white matter, the lamina multiformis is 

 alone much affected. Not only is this layer reduced in 

 breadth, but its constituent cells are reduced in size and 

 numbers. 



This type of cortex bears a considerable resemblance to 

 the temporal and some to the frontal cortex. It differs from 

 the latter, however, in many important points. It is of about 

 the same breadth but much richer in cells. The lamina 

 zoualis is narrower, the lamina grauularis externa more 

 clearly defined. The large pyramids at iii h are much more 

 numerous and form a more distinct layer. The lamina 

 granularis interna is also much richer in cells, and more 

 obviously separated from the adjacent strata. The lamina 

 ganglionaris is not so Avell developed, but the lamina multi- 

 formis is broader and richer in cells, and does not show the 

 gi-adual transition to the white matter which Brodmann 

 observes is a characteristic of the frontal lobe. 



Extent and Boundaries. — The inferior parietal cortex 

 lies behind and below the superior parietal both on the lateral 

 and on the mesial surface. On the mesial surface it covers a 

 broad area bounded in front by the sulcus subparietalis and 

 behind by the ramus parieto-occipitalis of the intra-parietal 

 fissure. Below it passes gradually into the posterior limbic and 

 occipital types. Above it passes over the supero-mesial border 

 and forms a narrow strip between the superior parietal area and 

 the upper end of the sulcus lunatus, then crosses the sulcus 



