20 T<>l''?^■■'^I- ^'^' CoMPARATUE NeUROLOGV. 



a ring or cap of cortex which entirely encloses the axial 

 lobe, which latter, by the encroachments of the ventricle, 

 has become separate from the walls. The cells of the oc- 

 cipital cortex resemble those of the fronto-median lobe (see 

 Fig. 5 B, Plate III). 



As already stated, the fronto-median and occipito-basal 

 lobes become continuous toward the dorson by circumscrib- 

 ing the intra-ventricular, which soon disappears. The re- 

 sult of the concrescence of the two areas and their subse- 

 quent increase in size is that nearly the caudo-median half 

 of the dorsal cortex is covered by the flask, or sensory type of 

 cells. 



The caudad portion of the lateral cortex is considerably 

 thickened, forming a distinct par ieial lode, of which the cells 

 seem to be pyramidal or multipolar and stain deeply. 



The intra-ventricular lobe is also quite prominent in the 

 fro^'-, forming a decided protuberance into the ventricle, and 

 consists of cells of the type having large clear nuclei and 

 fusiform outlines. Whether the function of these cells can 

 be safely predicated from their form may well be doubted, 

 but this much is certain, that these cells differ obviously 

 from those of the lateral aspects of the cerebrum. 



The fusion of the olfactory lobes with the cephalad part 

 of the hemispheres somewhat disturbs the arrangement, but 

 one may perhaps identify the homologue of the fronto- 

 median lobe in an anterior projection into the ventricle, 

 which is distinct from that just described, though filled 

 with similar cells. 



On the lateral aspect, the middle of the hemispheres 

 exhibit a series of concentrically arranged cells near the 

 ventricle and scarce and scattered pyramids in the ectal por- 

 tions of the mantle. Cephalad there is a distinct nidulus 

 ectad to the base of the olfactory protuberance. The cells 

 of this nidulus are rather flask-shaped than pyramidal. 



At higher (more dorsal) levels the occipito-basal and 

 fronto-median lobes fuse throueh the mediation of the in- 



