GENERAL CONSIDERATIONS. 



41 



Beference letters. 



ana anaate. 



1) buttress. 



cal callosum. 



oalo calcar. 



of couiiuis. 



cl callosal fiseure. 



col collateral. 



cor coronal. 



cr cruoiatfe. 



el ectolateral. 



f fimbria. 



g genual. 



bip hippocampus. 



1 lateral. 



marg marginal. 



mc medicoruu. 



ml - medilateral. 



pc postcornu. 



per poatcruciate. 



pi plexus. 



pro _. precoruu. 



prcr precruciate. 



prb postrbinal. 



prsp presplenial. 



prss presupersylvian. 



psp postsplenial. 



pss postsupersylvian, 



r rostral. 



rh rhinal. 



so superorbital. 



sp splenial. 



str striatum. 



Syl Sylvian. 



ss suijersylvian. 



tb tbalamus. 



iir ursine lozoDge. 



EXPLANATION OF PLATE V. 



Fig. 1. The ventral aspect of the brain of the fur seal, Callorkinus ursiniis, showing in addition to the 

 fissures the cranial nerves and the cerebellum. On each side of the latter is a depression 

 into which fits the petrosal portion of the temporal bone. 



2. The dorsal aspect of the brain, shoyring the cerebellum largely concealed by the cerebrum. 



3. The left lateral aspect of the cerebrum, 



4. The right lateral aspect of the cerebrum. 



5. The mesal aspect of the right hemicerebrum. 



6. The mesal aspect of the left hemicerebrum. 



EXPLANATION OF PLATE VI. 



F'ig. 1. The ventral aspect of the brain of the hair seal, Phoca vituUna, slightly modified from Tiede- 

 mann's figure. 

 2 The dorsal aspect of the cerebrum of Phoca vitulina, after Tiedemanu. 



3. The left lateral aspect of the cerebrum. 



4. The right lateral aspect of the cerebrum.- 



5. The mesal aspect of the right hemicerebrum. 



6. The mesal aspect of the left hemicerebrum. 



EXPLANATION OF PLATE VII. 



Fig. 1. The left lateral aspect of the cerebrum of the sea lion, Zalophus californianus. 



2. The right lateral aspect of the cerebrum of Zalopliua. 



3. The mesal aspect of the right hemicerebrum. 



4. The mesal aspect of the left hemicerebrum. 



5. The left lateral aspect of the cerebrum of Ursus thibetianua. 



6. The mesal aspect of the right hemicerebrum of Ursus. 



7. Dissection of the left hemicerebrum of Callorhinus, showing the lateral ventricle with a very 



rudimentary postcornu. 



8. Dissection of the left hemicerebrum of Phoca vituUna, showing the presence of the calcar and 



large postcornu in the lateral ventricle. 



