8o Journal of Comparative Neurology. 



in the bear ; the rima is narrow and the thalamus does not ap- 

 pear at all in the floor of the ventricle. A slight caudal spur 

 of the cavity at the medicornu represents the postcornu. The 

 splenial fissure, so to speak, just escapes the cavity, lying im- 

 mediately caudal to it. 



In the walrus Turner^ represents a dissection of this cavity 

 but shows no indication of a postcornu, but in the text he states: 

 "where the cavity of the ventricle curved downward and out- 

 ward into the horn, an indication of a recess was seen in its pos- 

 terior horn, but it did not amount to a cornu and there was no 

 elevation which could be called a hippocampus minor. " 



Murie,^ on the form and structure of the Manatee, figures 

 a well developed postcornu. He states that, " there is an un- 

 doubted posterior cornu, a fully developed hippocampus minor 

 and an eminence I am inclined to recognize as eminentia collat- 

 eralis. " The same author. On the Anatomy of the Sea Lion, 

 Otaria jubata, figures a more extensive postcornu than is repre- 

 sented in the manatee and describes it as "stretching backwards 

 and outwards with a very regular sweeping arch, and goes well 

 back into the occipital lobe, terminating in a shallow tapering 

 extremity. The eminentia collateralis is not distinctly defined ; 

 but what appears to represent the outwardly bulging hippo- 

 campus minor has a length of 0.7 of an inch, and at widest is 

 0.3 to 0.4 broad." 



Wilder in the Anatomical Technology, in indicating the 

 lines of inquiry likely to be most productive of results in the 

 homology of the human and feline fissures, states that "be- 

 tween the ordinary carnivora and the monkeys are two groups 

 whose brains should be studied with especial care ; the seals 

 have a rudimentary postcornu and occipital lobe, and these parts 

 are said to be developed in the Lemurs which have affinities with 

 both the carnivora and the primates." 



In none of the accounts have I seen any direct mention of 



' '84. Turner, Report on the Seals collected during the Voyage of H. 

 M. S. Challenger in the years 1873-1876. 



''■ 1874. Transactions of the Zoological Society of London. 



