NERVOUS SYSTEM. VERTEBRATA. 181 



I tentatively called " suprasylvian " is also seen to consist of 

 two limbs. Of these the posterior (as a study of this series 

 of Macropod brains shows) is much the more stable and 

 represents in all, probably, the suprasylvian sulcus of other 

 Orders, in spite of the fact that its topographical relations 

 are so peculiar. The anterior limb of the V may represent 

 the coronal sulcus of the Carnivora and Ungulata. We 

 can also see a transverse sulcus extending inward from the 

 angle of the V, just as we sometimes find in the actual 

 brain (see D. 211). It is interesting to note that there is a 

 large shallow depression in the place of the lateral (" para- 

 medial ") sulcus a fact which is not demonstrable in the 

 actual brains. This is of great interest when the peculiar 

 absence of this sulcus in the larger, and not in the smaller, 

 Macropods is recalled. There is a deep, long, postlateral 

 sulcus. 



D. 216. The brain of a Parry's Wallaby (Macropus parryi] . 



A short deep " Sylvian fissure " sulcus A extends 

 almost vertically upward from the bend of the rhinal 

 fissure (figs. 58 and 59) . 



Fig. 58. (Nat. size.) 



SULC.SUPRAS 



SU1C.PARAM 



SULC.PROR. 

 -SUtC ORB. 



The orbital (presylvian) sulcus and the sulcus B both 

 spring from the rhinal fissure, and diverge widely as they 

 ascend. On the left hemisphere the short extent of the 

 true orbital sulcus is seen, because it is not joined to the 



