130 



Drs. Mott, Schuster, and Halliburton. [Oct. 20, 



temporal lobe a comparative poverty of cells is noticeable, both in the 

 pyramidal and granule layers. Posteriorly the pyramids are smaller and 

 more crowded, and in both regions the large pyramids are greatly diminished 

 in size. 



Visual Area. Extent and Boundaries. — The visual area covers the posterior 

 pole of the hemisphere. It extends forward on the external surface for about 

 3 or 4 mm., and on the mesial surface to about halfway between the pole 

 and the corpus callosum, as shown in fig. 1. 



Characteristics. — The depth of the cortex is about 1'5 nun., the molecular 

 layer measuring about 0"1 mm., the pyramidal layer about 0"6 mm., the 

 granule layer 0"3 mm., the line of Gennari O'l mm., and the polymorph layer 

 0*3 to 0-4 mm. The pyramidal cells are rather smaller than those of the 

 motor and temporal types, and more numerous, and the granules also are 

 smaller and more crowded. Large solitary cells of Meynert, measuring about 

 20 yit by 15 fi, are scattered above and below the granules. 



In the Lemur the visual cortex is more shallow, and the individual cells are 

 smaller and more closely crowded together. 



Archipalliuvi. Olfactory Area. Extent and Boundaries. — The olfactory 

 area lies on the under side of the anterior portion of the temporal lobe, the 

 rhinal fissure forming its inferior and anterior, and the hippocampal fissure 

 its superior boundary. Posteriorly it extends to about the level of the 

 extremity of the rhinal fissure. 



Characteristics. — This cortex measures about 1 nun. in depth, the mole- 

 cular layer measuring about 0'2 mm., the pyramidal layer about 0*4 mm., the 

 pallid zone about 0"1 mm., and the polymorph layer 0"3 to 0'4 mm. Thus, 

 though the cortex as a whole, and the pyramidal layer particularly, are 

 more shallow than in the neopallium, the molecular layer is deeper. A 

 line of characteristic cells lies at the top of the pyramidal layer, larger 

 than the adjacent pyramids, they are more closely crowded together, and 

 form a characteristic darkly staining line under a low power of the 

 microscope. They are angular, and generally quadrilateral in shape, and 

 have several clearly staining branched processes, of which two generally 

 pass upwards into the molecular layer. The pyramidal cells as a wliole 

 are comj)aratively large, though they are not numerous; but there is 

 no line of specially large su])ra- or infra-granular pyramids. Scattered 

 granules are seen among the ])yrami(Is, but do not form a distinct grainile 

 layer. X conspicuous pallid zoni; lies below the pyramids. The iKjlyuiorph 

 layer is composed of blunt roundish cells, similar to Lhosc found in tho limbic 

 area. 



Limbic Area. Extent and P.oundarics. — The limbic area covers tho ])ortiou 



