120 THE VOYAGE OF H.M.S. CHALLENGER. 



fissure by a short retrolimbic gyrus. In both the Weasel and Ferret the marginal part 

 of the sagittal convolution was much narrower than the callosal convolution. In both, 

 also, the olfactory apparatus was largely developed. In the Coati, Weasel, and Ferret, 

 the relations of the sigmoid gyrus to the coronal fissure, and of that fissure to the 1st 

 curved fissure, closely corresponded to the arrangement in the Badger and Eatel. 



I have examined in the Felidse the tentorial and mesial surfaces of the hemisphere 

 in the brains of the common Cat {Fells domesticus) and the Tigef (Felis tigiis). In the 

 Cat one retrolimbic gyrus, and in the Tiger two, separated the splenial from the post- 

 rhinal fissure, and in the latter a third bridging convolution crossed the splenial fissure 

 immediately behind and above the splenium. In both, the crucial fissure was situated 

 in the anterior part of the dorsum of the hemisphere, and was not joined by the splenial 

 fissure, which in both animals reached the margin of the hemisphere behind the crucial 

 fissure. In neither animal was there an ursine lozenge. In the Tiger the convolutions 

 were more subdivided by secondary fissures than in the Cat, and on the tentorial surface 

 both a postsplenial fissure and a splenial convolution were present. Both animals had 

 a large olfactory apparatus connected by a strong tract with the uncinate convolution. 



In the common Cat the coronal fissure was short and cut off by an intermediate 

 narrow gyrus from the prsesylvian fissure in front and the 1st curved fissure behind ; it 

 bounded the sigmoid gyrus externally. In the Tiger, in which the sigmoid gyrus was 

 large and tortuous, the coronal fissure formed its outer boundary, and though not pro- 

 longed forward into the prsesylvian fissure, it was continued backwards into the 1st curved 

 fissure. In both the Cat and Tiger the sagittal convolution was continuous with the 

 posterior limb of the sigmoid gyrus. 



It is well known that in the Felidse the differentiation of the convolutions on the 

 cranial surface of the hemisphere into four tiers is not so precise as in the Canidas. The 

 convolution which bounds the Sylvian fissure is, in all probability, homologous in both 

 families. In the Tiger the suprasylvian convolution was differentiated in its whole length 

 from the Sylvian convolution by the suprasylvian fissure, and from the sigmoid gyrus 

 and sagittal convolution by the 1st curved fissure. There was no distinct mediolateral 

 convolution, but a convolution which might represent it was partially differentiated from 

 the sagittal convolution by an imperfect mediolateral fissure.. In the common Cat the 

 sagittal and the 2nd external convolution were distinctly differentiated from each other 

 by an intermediate fissure, but the Sylvian and suprasylvian convolutions were partially 

 blended together, especially in their posterior limbs. 



In the series of brains examined the coronal fissure was seldom continued forward 

 into the prsesylvian fissure, but it was very frequently prolonged backwards into one of 

 the curved fissures on the cranial aspect of the hemisphere, 1 though sometimes it was 



1 In Leuret's figure of the brain of the Lion, the coronal fissure is continuous with the 1st curved fissure, but in 

 Victoria Familiant's figure of the brain of this animal these fissures are separated from each other, as in the common 

 Cat, by an intermediate bridging convolution. 



