68 Journal of Comparative Neurology. 



the paroccipital of man. This occurs on the left hemicerebrum. 

 On the right the postsplenial has much the same appearance. 



At the cephalic end of the mesal surface beyond the genu 

 of the callosum, there are two pretty well marked fissures. The 

 one nearest the callosum corresponds to the genualis of Krueg, 

 part of falcial — Owen, or falcial — Wilder. On each hemicere- 

 brum this fissure cuts the dorsal margin slightly. The other 

 and more slightly developed fissure lies nearer to the olfactory 

 bulb. It does not reach the dorsal margin but extends farther 

 in the ventral direction. This fissure corresponds to the rost- 

 ralis of Krueg, part of falcial — Owen, subfalcial — Wilder. 



PHOCA VITULINA. 



The frontal portion of the cerebrum is more foreshortened 

 than in Callorhimis and there is therefore a slightly different ar- 

 rangement of corresponding fissures in that region. One of the 

 most striking differences is the olfactory portion of the brain. In 

 Callorhinus it is the larger, the olfactory bulb is of considerable 

 size, the crus is correspondingly wide and lies fliush with the 

 mesal surface. In Phoca the bulb is relatively smaller and the 

 crus has atrophied to scarcely more than a pedicle, it lies deep- 

 ly imbedded in the olfactory fissure and it is removed 6-8 milli- 

 meters from the mesal surface by a portion of the cortex which 

 projects fully 5 millimeters beyond the crus. 



The precribrum (anterior perforated space) is well devel- 

 oped and shows with greater distinctness than in Callorhinus. 

 The rhinal fissure is apparently continuous with the Sylvian, but 

 upon raising the overlapping portion of the frontal lobe, it is 

 seen to maintain its continuity and to appear again caudal to the 

 Sylvian as the postrhinal, differentiating a larger pyriform 

 lobe than in the case of CallorJiinus. There is no connection 

 between the postrhinal >and the subfissure in the caudal wall of 

 the Sylvian as in CallorJiinus. 



Lateral Aspect. The Sylvian fissure pursues a much more 

 obliquely dorso-caudal course than in CallorJiinus and presents 

 the same amount of complexity with relation to the surround- 

 ing fissures. In its caudal wall lies a subfissure (postica ?) and 



