1910-11.] Topography of Cerebral Cortex of Guinea-pig. 
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Type I. ( -J- + + ) lying at the posterior pole. 
Depth of cortex 1*5 mm. 
1. On the surface is a zone of very small, faintly stained cells, lying in a 
non-stained fibrous network. Since this zone is common to all the types, it 
will merely be referred to as Zone I. in the descriptions of the remaining 
types. 
Anterior pole. 
Fig. 1 . — Upper surface of cerebral hemisphere, showing the distribution of the various types of 
cortex described in the text. 1, Sylvian fissure ; 2, lateral fissure; ++, cortex, Type I. ; 
x x, cortex, Type II. ; •#, cortex, Type III. ; ©CD, cortex, Type IY. ; OO, cortex, 
Type Y. 
2. A thick zone of irregular round or polygonal cells distinctly larger 
than the cells of the first zone. 
Fig. 2. — Mesial surface of cerebrum, c.c., corpus callosum ; P.L . , pyriform lobe ; s.c., section 
through crus cerebri; L.L., position of limbic lobe; ++, cortex, Type I. ; x x, cortex, 
Type II. ; ® ®, cortex, Type IY. ; OO s cortex, Type V. 
2'. A narrow irregular zone of very small pyramidal cells. 
3. A narrow granular zone; this zone varies much in depth but is 
nowhere prominent. It corresponds to the granular layer of Bolton. 
