144 ON THE POUCH ETC. OF THE MALE THYLACINE. [Feb. .3, 



quarter of an inch in front of it. On the right hemisphere this 

 fissure is slightly different, as will be seen from a comparison of 

 figs. 2 and 3, and the indentations on the posterior lobe are a little 

 better marked. 



The second furrow is continuous with the rhinal furrow just in 

 front of the Sylvian fissure ; its course is much the same on both 

 sides of the body. The anterior lobe of the brain cut off by this 

 fissure is U-shaped, a longitudinally running furrow nearly dividing 

 it into two. 



Sir William Turner ^ remarks that " the configuratiou of the 

 brain and the pattern of the convolutions have followed in each order 

 a process of evolution characteristic of the order, the arrangement of 

 the conTolutions does not follow the same plan in the various orders. 

 Hence, in the comparison of the brains of mammals with each other, 

 diversities often are recognized which make it impossible to determine 

 the presence of precisely homologous fissures and convolutions in the 

 whole series of the Gyrencephala." 



It appears to me that this statement might also be extended in 

 the case of the Marsupials to a single order ; it is extremely 

 difficult to compare the convolutions of the brain of Thylacinus with 

 those of the brain of Macropus. 



The points which they have in common are: — (I) The strongly 

 marked and continuous rhinal fissure ; but this is found in most 

 mammals. (2) The separation of an anterior lobe {cf. fig. 2, p. 141) 

 by a transverse fissure ; such a lobe is not for example to be seen in 

 the brain of Dolichotis, nor is it of course to be seen in the 

 " lissencephalous " Koala &c. Judging from Gerrais's figures this 

 lobe was particularly conspicuous in the extinct Thylacoleo. 

 M. Gervais's observations upon the cast of the brain of this latter 

 Marsupial are of particular interest in relation to a well-known 

 controversy. I may remark, however, that the brain of Thylacoleo 

 appears to have differed from those of the Wombat and Kangaroo 

 no less than from that of the Thylacine by the outivard direction 

 of the longitudinal furrow dividing the anterior lobe. However, 

 in Halmaturus bennetti the furrows in question are intermediate 

 between the two extremes, being straight. It appears to me that 

 Halmaturus and Hypsiprymnus come much nearer to Thylacoleo 

 than the Wombat does in the form of their cerebral convolutions. 

 M. Gervais himself considers that the Wombat is the closest ally 

 of Thylacoleo in these points of structure. (3) In common with 

 many other lower mammals, the lobus hippocampi is not marked by 

 furrows, and is not covered by an extension downwards of the 

 palHum. Finally, of course, there are the important differences in 

 the commissures. 



With the exception of the Sylvian fissure and the sulcus which 

 divides off the anterior lobe of the brain and the rhinal furrow, it 

 seems to me to be very difl[icult to compare the furrows and 

 convolutions of Thylacimts with those of the Diprotodont Marsupials. 

 The Sylvian fissure is directed at first slightly forwards, and then 



' Loo. cit. p. 152. 



