THE BKAIN IN THE EDENTATA, 



373 



in between the areas A and C we find at the dorso-lateral corner of the anterior surface 

 (fig. 30) a little group of about six folia wliicli converge in a mesial direction toward the 

 lateral corner of the medullary area on the dorsal surface (Bg. 31). The resemblance 

 between the cerebellum in Xeuurus, the Rodent Lepus, and the Marsupial Dasi/urus is 

 very striking. 



In Dasi/jms we find that the lobits centralis does not cover the lobus anticus so 

 completely as it does in Xeuurus. Thus the Jissura jirlma and part of the anterior lobe 

 become visible ujion the dorsal surface. The area B of the central lobe, instead of being 

 almost confined to the anterior surface, now forms the extreme lateral angle of the dorsal 

 surface. la other words, the organ becomes much more like the cerebellum in the 

 JIanidce and BradypocUdcB. We see the same process occurring in tlie Rodents. Eor 

 while Lepus is like Xenurus in this resjject, we find that in Atherura * a cei'ebellum in 

 many res^^ects like that of Ta-maudua is found. 



In Dasi/pus \\\<i parafloccidus dorsalls is relatively larger than in Xenurus. 



In Clilami/dophorus the cerebellum presents a very peculiar appearance (fig. 15). It 

 is a flattened plate closely applied to the vertical posterior extremities of the hemispheres, 

 and appears at a cursory glance to be utterly unlike any of the other forms we have so 

 far considered. But ^vhen we study its anatomy more closely, by means of sections, we 

 find that it is merely a simplified type of the cerebellum of Xenurus which has become 

 flattened between the vertical occipital plane of the skull and the posterior extremities of 

 the hemispheres. An exactly similar flattening takes place in the Marsupial Notoryctes. 

 A lohus JloccuU composed of about six simple foHa is placed like a buttress against the 

 lower part of each lateral edge of the cerebellum (figs. 15, 35, and 30). 



Yxs. 34. 



- lob. central. 



fiss. prima 

 lob. aut. 



vel. meduUare »v--v\-ma 



-Bss. secunda 



. lob. post. 

 Mesial sagittal section of cerebellum of Chlamydophorus. Enlarged 3 (liam. 



FiK. 3.5. 



lob. post. 



Anterior surface of cerebellum of Clilaiuydophorus. Enlarged 2 duira. 



* F. G. Parsons, " On the Anatomy of Atherura africanu," Troc. Zool. Soc. London, 189-1, p. 087, figs. .5 & 6. 

 SECOND SERIES. — ZOOLOGY, VOL. VII. 51 



