1909.] Cortical Lamination, etc., in Brain of Marmoset. 129 



movements of the head and eyes, month, side of face and tongue and pricking 

 of ears were obtained by stimulating a cortex similar in position and 

 structure ; though in the case of the Lemur the essentially sensory type of 

 the cortex, though recognisable, was not so pronounced. 



Post Central Area {fig. 5). Extent and Boundaries. — The post central 

 type lies behind the motor, covering only a relatively small external area ; 

 but on the mesial surface it spreads out and extends farther down than the 

 motor type, and is found wedged in between the posterior part of the motor 

 and limbic areas. These boundaries are only approximate, as it is extremely 

 difficult .to distinguish the peri-focal area of this type of cortex from the 

 surrounding intermediate types. 



Characteristics. — The depth of the cortex is about 1'4 mm. ; the molecular 

 layer measuring about 0*12 mm., the pyramidal layer about 0"6 mm., the 

 granules 0'15 mm., and the polymorph layer about 0'4 mm. The molecular 

 layer is slightly deeper than in the motor area, and the pyramids as a whole 

 are rather smaller, more regular, and more numerous. There is a distinct 

 band of granules which distinguishes this area from type motor A, and it 

 may be noticed that there is no distinct pallid zone, such as that in which 

 the Betz cells He. The pyramidal cells above the granules are not of 

 remarkable size, but a characteristic line of large plump infra-pyramidal 

 cells is conspicuous, the largest measuring about 35 jx to 20 jju. 



Temporal Area {fig. 6). Extent and Boundaries. — A temporal type of 

 cortex probably covers the temporal lobe from the Sylvian fissure on the 

 external surface to the rhinal fissure on the underside. It is bounded 

 superiorly by the Sylvian fissure, anteriorly by the rhinal fissure. On the 

 under surface and posteriorly it merges gradually into the intermediate 

 areas lying between the temporal and visual types. But the cortex is only 

 seen in its most typical form on the external surface below the Sylvian 

 fissure, as marked on the diagram by the blacker crosses (fig. 1). 



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

 layer measuring 0-12 mm., the pyramidal 0 6 to 07 mm., the granules 

 about 0-25 mm., and the polymorph layer about 0"5 mm. 



In the most typical region the cells of the pyramidal layer, like those in 

 the motor area, are of relatively good size, and are neither very numerous 

 nor regular in arrangement as compared with other regions. The most 

 conspicuous feature of this area is the presence of large, attenuated, deeply 

 staining pyramidal cells, the biggest measuring about 40 /it by 10 jx. These 

 are found both above and below the granules, but are more numerous above. 

 The granule layer is deep and very rich in cells. In its peri-focal area the 

 cortex becomes less typical. As it approaches the anterior extremity of the 



