40 



THE FUR SEALS OF THE PRIBILOF ISLANDS. 



of casts), notwithstanding the fact that the bulk of the body of the male is about four 

 times as great as that of the female. 



Of the representatives of the four groups examined, the brain of Callorhinus 

 shows a greater number of minor fissures and a more intricate arrangement and 

 branching of the larger fissures. 



With regard to the ground plan of the fundamental fissures, and allowing for 

 the ditterence in the shape of the brains, that of the eared seals — GaUorh'uius and 

 Zalophus — approximate in general more closely to that of the ursine carnivora than 

 does rhoca. The latter, or earless seal, in some respects appears aberrant. The 

 arrangement of the cruciate and postrhinal fissures would seem to link it with the 

 canine and feline carnivora, while tlie peculiar development of the occipital region 

 and the large development of the postcornu with its calcar point toward primate 

 conditions. The group of lemurs is also said to i)0ssess a postcornu and to have 

 affinities with both the carnivora and the primates. 



As a matter of convenience, a table of the more interesting regions in the repre- 

 sentatives of the dittereut groups examined is herewith appended: 



Kegion. 



TJreus. 



Zalophus. 



Callorhinus. 



Monachus. 



Phoca. 



1. Snbfissiire pos- 



tita. 



2. I'ostrliiiial 







Pre-sent 



Not very distinct . . . 



Present. 



C'oiitiiitiatiou of 



Continuation of 



Continuation of 



A mere trace, very 



Continuation of rhi- 





rlii nal , excep- 



po.slica. 



postica. 



superficial con- 



nal. 





tionally of pos- 







nection with pos- 







tica. 







tica. 





3. P r 6 s 11 !> e r ■ 



Continuous with 



Continuous with 



On left heniicere- 



Connected with su- 



Disconnected. 



sylvian. 



siipersylvian. 



supersylvian. 



briiiii of pup, 

 disconnected, 

 but usually con- 

 tiniiuus. 



persylvian. 





4. Posts u per- 



do 



Continuous 



Disconnected 



In four ln'micen;- 



Continuous , but 



sylviau. 









b r 11 in s ; t w o 



with indications 









.showed a (connec- 



of shallows. 











tion and ihir other 













two a disconnec- 













tion. 





5. Prccruriato 



6. Cruciate 



if cstlv dorsal 



Dor.sai, just tut- 



Dorsal . .... 



Dorsal 



Mesal and dorsal . .. 



Not dearly shown. 



do 



do 



Dorsal and nicsal . . . 



Dorsal and mesal. 





ting niesal raar- 











7. Postcruci.ite ... 



8. MiiiorfiSsuris.. 





Present 



Present 



Rudimentary 



Present. 



I{.in- 



Not many 



Xumerous 



Quite iiuiiKTOus 



Quite nuiiierous. 



9. "Ur.sino Loz- 

 .•Dg.-.' 



10. Postcoriiu 



11. Calcar 



12. Medilateraltis- 



Present 



Present 





Small 



Absent. 



Small 





Very large. 

 Very distinct. 



do 





Absent 



Present 







Present 



Present 



A series of small 









disconnected fis- 













sures. 



13. Marginal fis- 

 sure. 





do 



do 



A series of short 



Present. 









interrupted fis- 













sures. 





14. CoUateral fis- 

 sure. 



do 





. do 



Present 



Present, but con- 











nects with post- 













rhinal. 





Slight 



Slight 



Slight 



Slight 



Slight. 













