CEEEBEAL CONVOLUTIOKS Or THE CAEKIVOEA.. 15 



P. Gervais *, but is neitlier described nor figured by Mm, nor do 

 I know of any publisbed representation of it. The Sylvian fissure 

 is long and oblique. The Sylvian gyrus is very much broader 

 posteriorly, the anterior limb being exceedingly narrovp. The 

 parietal gyrus is quite simple, and its anterior and posterior limbs 

 are about equal. The sagittal gyrus is enormously expanded 

 anteriorly. Its most j)osterior part is quite simple and single, 

 but behind the crucial sulcus it is longitudinally grooved. It 

 then doubles backwards and afterwards curves forwards in com- 

 plex convolutions, surrounding the crucial sulcus. The latter, 

 which is well developed, sends forwards secondary sulci, and so 

 forms a rather elongated " Ursine lozenge." 



The supraorbital gyrus (fig. 3, 0) is large, and bears a T-shaped 

 or T-shaped vertical sulcus {T). 



The calloso-marginal sulcus does not join the crucial one, but 

 a very narrow bridging convolution connects the hippocampal and 

 sagittal gyri behind the crucial sulcus. 



Galictis f. — In the Tayra, the part of the cerebruna which is 

 anterior to the crucial sulcus is smaller than in MelUvora. 

 The upper surface of the brain is singularly complicated by 

 supplementary depressions, and by bridging convolutions which 

 connect the parietal and sagittal gyri, so that it is very difficult 

 to determine which gyrus of the two is the one which is the 

 more broadened and complicated anteriorly. Indeed, it seems 

 impossible to draw any well-defined boundary between them. 

 The Sylvian fissure is oblique and prolonged. The Sylvian gyrus 

 is simple, and has its anterior limb very decidedly the narrower. 

 The parietal gyrus, if it could be considered simple, must be 

 said to blend with the sagittal gyrus by several bridging convo- 

 lutions. The sagittal gyrus must then be considered as very 

 wide, and as bearing two longitudinal grooves at its middle part. 

 It blends, as just stated, with the parietal sulcus, and expands 

 widely as it advances forwards. Its hindmost part is very 

 broad, and bears a median longitudinal groove. The crucial 

 sulcus sends forwards, on either side, a groove to define a small 

 "Ursine lozenge." It is not joined by the calloso-marginal 

 sulcus, a bridging convolution connecting the hippocampal and 

 sagittal gyri behind the crucial sulcus. 



* See I. c. p, 145. 



t Eeferred to by P. Gervais, I. c. p. 144. He giyes no figure. 



