Fish, Brain of the Ftir Seal. JJ 



postsplenial in the seals. A slight spur in this region in the 

 bear may indicate an analogy. 



The presplenial is not represented as a distinct fissure on 

 the left hemicerebrum, the only possible suggestion of it being 

 a forking at the cephalic end of the splenial. On the right hemi- 

 cerebrum a small but distinct fissure lying cephalad of the sple- 

 nial may represent the presplenial. 



The marginal fissure is well represented and on both hemi- 

 cerebrums cuts the dorsal surface as in CallorJiimis. In PJioca 

 although relatively long it does not reach the dorsal margin at 

 all. In the bear the marginal fissure is not represented. 



The genual and rostral fissures are but slightly developed 

 in this specimen and bear the same relations as in other forms. 



The cruciate fissure shows slightly on the mesal aspect and 

 in its relations to the other parts resesembles that of the bear 

 more than any of the others. 



FISSURAL INTERPRETATIONS OF OTHER WRITERS. 



The Sylvian fissure, in Phoca at least, has been located as 

 a vertical fissure (presupersylvian) which has, for a portion, only, 

 of its length, been submerged in the cephalic wall of the true 

 Sylvian. Numerous writers have also described this condition 

 as the anterior and posterior branches of the Sylvian. The two 

 fissures morphologically are entirely distinct. In Hyrax Krueg 

 does not represent any indication of a Sylvian fissure whatever. 



The supersylvian is very commonly called the suprasylvian. 

 Leuret et Gratiolet have confused this fissure with the lateral 

 in Phoca. 



Following Krueg the fissure which is designated as the post- 

 supersylvian, is commonly known as the postsylvian of Owen. 

 What I have designated as the presupersylvian and which is 

 only exceptionally independent, is usually described as the an- 

 terior or frontal portion of the supersylvian. 



A fissure corresponding to the coronal is represented by 

 Krueg as the presylvian in Phoca. Kiikenthal makes a similar 

 representation. Turner in MacrorJmius represents a correspon- 

 ding fissure as the presylvian and a branch connecting with it 



