244 PHYSIOLOGICAL SERIES. 



the upper lip of the rhinal fissure. Thi< arrangement is 

 similar to that presented by the brain of Iferpestes. 



The eetosylvian sulci are very deep, as if to compensate 

 for the diminutive size of the pseudosylvian. The anterior 

 and posterior ectosylvian sulci appear to be joined into an 

 arc on both sides as in Cynoidea ; but they are in reality 

 separated by a feline gyrus which is partly submerged. 

 There are a series of fragmentary sulci between the posterior 

 ectosylvian and the postsylvian. The postlateral is a short 

 branch of the latter sulcus, and is quite independent of the 

 lateral sulcus. The latter is continuous on the left side 

 with a long and tortuous coronal sulcus. There are well- 

 marked but shallow representatives of an ontolateral sulcus 

 on each hemisphere. 



This specimen is of special interest as a further demon- 

 stration of the fact, which has already been noted in the 

 Sloths and the lowlier Mammalian Orders generally, that 

 the " Sylvian fissure " (so-called) is at first a very unstable 

 feature and only becomes definitely " fixed " in the higher 

 Mammalia. It further illustrates the reciprocally com- 

 pensatory development of the pseudosylvian and the ecto- 

 sylvian sulci, of which we meet many instances elsewhere*. 



D. 293. The brain of a new born Lion (Felis leo). 



The only noteworthy features in this specimen are a series 

 of peculiar notchings in the upper lip of the rhinal fissure 

 in front of the pseudosylvian sulcus, and the extreme 

 irregularity of the latter and of the ectosylvian sulci. 



0. C. 132. r > A a. 



D. 294. The brain of a Lioness (Felis leo), in which a dissection 

 has been made to show the hippocampus in the left hemi- 

 sphere. 



The brain of the Lion when compared with that of the 



a fiords an admirable demonstration of the inline! 



In the accentuation of tha ecto- at the expense of the paeudosyh inn 

 sulcus this anomalous brain resembles the Ungulate type, the so-called 

 " Sylvian fissure " of which is formed by the meeting of the lips of thf t\v<> 

 ectosylvian sulci. In this case also the feline pseudosylvian sulcus bccuii<- 

 greatly reduced or even disappears. 



