526 MR. F. E. EEDDARD ON THE BRAIN AND [June 14, 



on both sides ; about half an inch away from the intestine a fold 

 arises from the mesentery supporting the intestine, which crosses 

 over the intestine itself and is attached to the caecum ; a deep 

 pocket is thus formed which is of course floored by the caecum ; on 

 the opposite side there is a corresponding fold, arising, however, 

 rather further away from the intestine ; this also crosses the intes- 

 tine and becomes fused with the fold running directly from the 

 intestine to the caecum. The caecum is thus supported by three 

 distinct folds, of which the median one, that arising from the 

 intestine, is practically anangious ; the two lateral folds which arise 

 from the mesentery on the side furthest away from caecum bear 

 blood-vessels. 



III. Brain. 



The brain showed, after preservation in alcohol, the following 

 proportions : — 



Total length (to end of cerebellum) 37 mm. 

 Length of hemispheres 24 mm. 

 Greatest breadth 24 mm. 

 Vertical diameter 16 mm. 



The outline of the brain as seen from above is shown in the 

 accompanying drawing (woodcut, fig. 2). The two hemispheres 



Fig. 2. 



Brain of Aulacodus, viewed from above. 

 Sy, Sylvian fissure ; a, longitudinal furrow. 



are broader behind than in front ; up to the Sylvian fissure the 

 outer borders of the two hemispheres are approximately parallel to 

 each other, though their outline is, of course, curved ; from the 

 Sylvian fissure to the anterior extremity of the brain these margins 

 converge slightly, the diameter of the anterior extremity of the 

 brain being 1 1 mm. The form of the hemispheres is in fact more 

 like that of Octodon and Myopotamus among the immediate allies 

 of Aulacodus : there is less similarity in the general shape of the 



