1905.] 



The Mammalian Cerebral Cortex. 



153 



behind the anterior pole to about the posterior quarter of the hemisphere, 

 and laterally from the dorso-mesial margin (or more or less close to this 

 anteriorly and overlapping this posteriorly), to about half-way between the 

 dorso-mesial edge and the rhinal fissure, the lateral limits varying somewhat 

 at different points (figs. 1 and 2). 



Area II: General Sensory. — This occupies an extensive region lateral to 

 Area I, but does not reach as far as the rhinal fissure, being separated from 

 the latter by a zone of undifferentiated cortex (fig. 1). 



The features of Area I are less characteristic mesially, anteriorly and 

 posteriorly, and of Area II anteriorly and posteriorly. These two fields 

 appear in every way to be the best developed areas of the neopallium and 

 to be amongst the oldest, phylogenetically. Owing to their different 

 histological appearances, Areas I and II in the Mole can be readily 

 delimited. From the relatively greater numbers and prominence of the 

 large cells (homologues of Betz cells) in Layer IV, it is concluded that 

 Area I possesses especially motor attributes, and that on account of the 

 greater development of the granular layer throughout Area II, the latter 



Fig. 2. — Postero-mesial aspect of the Left Hemisphere of the Mole, to illustrate especially 

 the position and relations of the postero-mesial legion of cortex characterised by a 

 well-marked granular la^er. The right-hand figure is explanatory of that on the left. 



is sensory in function. It is also thought that probably Area II is largely 

 concerned with kinpesthetic impressions, these appearing to constitute a 

 considerable part of the basis of such intelligence as these animals possess. 

 In the Hedgehog, although interpretation of the cortical structure is much 



