JIORPHOLOGT OF THE BRAIX IN THE MA:\IMALIA. 



355 



The olfactory liull) is a flattened cake-like mass 9 mm. wide and 11 mm. long, and 

 resembles that found iu the Indrisinte and in the genus Lemur. it is, howev'er, 

 completely overlajiped by the cerebral heraispliero, as Ouderaans and Chudzinski have 

 already pointed out ; Gervais's representation of it projecting' beyond the hemisphere 

 like that of Lemur is clearly erroneous. 



About as much of the cerebellum is uncovered by the cerebrum as we have noted in 

 one specimen of Lemur /ulcus (fig. 3). 



The arrangement of the cerebral sulci presents some most extraordinary features : 

 it is, moreover, especially noteworthy by reason of its extreme variability. The plan of 

 the fui'rows is so puzzling that no writer on the brain of Chlromys has ventured to 

 compare it in detail with that presented by other Lemurs. Thus, Owen makes use of 

 the nomenclature used in describing the brain in the Carnivora; Gervais compares it with 



Fig 32. 



Clt Iroinijs madarjascariensis. 

 The dorsal aspect of the braiu. Slightly enlarged. 



that of Ailurus ; Oudemans likewise employs Krueg's nomenclature for the Carnivore- 

 brain; Chudzinski also is driven to a comparison with the cerebral pattern in the same 

 Order ; and, finally, A. J. Parker * quotes with approval the opinion of Pansch that the 

 Aye-aye belongs to the group of mammals which includes the Carnivora. 



The chief reason for all this hesitancy in comparing the svdci of this brain with those 

 of the other Primates depends upon the fact that in Cldromys the suprasylvian sulcus 

 has become widely separated from the pseudosylviau sulcus, and the latter is exhibited 

 in different specimens iu various stages of disintegration. Thus there is no typical 

 Svlvian fissure ; and the failure to recognize that the latter consists (in the other 

 Primates) of an apparent blending of the suprasylvian and pseudosylviau sulci by the 

 submergence of the region between the overlapi)ing parts of these furrows {vide supra) 

 naturally gives rise to confusion w'hen the intervening area is not submerged, as is the 

 case in Chiromys. This separation of suprasylvian and pseudosylviau sulci also makes 



* Journ. Acad. Philad. ser. 2, s. IS'JC. 



