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multipolar cells resembling those of the second olfactory 

 or rhinomorphic type, not exceeding .010 mm. in greatest 

 diameter. 



The occipito-basal lobe in the black-snake is much more 

 complicated, and, in order to understand it, a description of 

 the topography of the entire cerebrum may be necessary. 

 The hemispheres are strongly protuberant and abbreviated. 

 The cephalad portion is suddenly constricted and applied 

 laterad to the apparent crus of the olfactory, so that a con- 

 siderable portion of the cortex actually extends out upon 

 the olfactory lobe. The olfactory structures proper accumu- 

 late at the mesad surface, where they are strongly devel- 

 oped, while the laterad portions cephalad are reduced to a 

 thin film of fibres. The result of this peculiar limitation is 

 that the large olfactory ventricle curves laterad from the 

 base to near the tip, where it abruptly arches mesad, so 

 that the olfactory fibres take their origin from the mesal 

 surface, toward which the glomerulary layer presents a con- 

 cavity for their reception (Cf. Plate X, Fig. 6). 



The concentration of the cortex caudad accounts, partly 

 at least, for much that here follows. The ventro-basal pro- 

 tuberance of the hemispheres, which seems analogous in 

 position to the pyriform lobe of Rodents, for example, con- 

 tains a concentric zone or hollow spheroid of gray matter 

 greatly (though spuriously) resembling the hippocampus. 

 This concentric mass of cells, which makes up the major 

 portion of the occipito-basal lobe, contains fusiform cells 

 which in some places are rapidly proliferating. Cephalad 

 to it lies a dense cell-mass representing the central division 

 of the axial lobe. Dorsally the concentric caudad portion 

 becomes quite distinct from the non-concentric cephalad 

 body. There is also a small latero-caudad cluster ectad 

 to the occipito-basal lobe, and it, like the ventral and 

 cephalad parts of the central lobe, contains pyramidal cells 

 predominatingly. 



In the lizard a tract can be traced to the region of the 



