1895.] 



ME. F. E. BBDDAED ON THE BBAIX OF GULO. 



Ul 



Arctoidea, the anterior limb of the Sylvian gyrus is the longer. 

 This is particularly marked above and leads toward the condition 

 characteristic of Meles and Nasua, where the anterior limb of the 

 Sylvian gyrus has the appearance of being tucked away in its upper 

 part below the surface of the brain. 



The parietal gyrus is connected by a bridging convolution with 

 the sagittal gyrus. This is perfectly symmetrica] on each side of 

 the body and lies anteriorly on a level with the upper extremity of 

 the Sylvian gyrus. At its extreme anterior end this gyrus becomes 

 continuous with the Sylvian gyrus and, on one side, with the 

 sagittal gyrus again. 



The sagittal gyrus, as is the rule with the Arctoidea, is wide 

 and complicated. That part of the gyrus which is at right angles 

 with the rest, and reaches the margin of the pallium, is divided by 

 a longitudinal furrow, of which there are only traces in Gcdictis 

 and Nasua and no traces in Meles. 



Braiu of Gulo (side view). 

 Sy, Sylvian fissure ; c, crucial sulcus. 



I now come to the crucial sulcus (c), which is so important in 

 the Carnivorous brain and especially in the Arctoid. 



As in all Arctoidea, which are thus differentiated from the 

 Ailuroidea, the crucial sulcus is situated comparatively far 

 back. In Gulo the proportions of the lengths of the precrucial 

 and postcrucial regions are 28 : 40. In Meles and Taxus they are 

 more nearly equal, being 26 : 30. On the other hand, in Galictis 

 they are 14 : 34. In Gulo, as in Galictis, the crucial sulci are 

 nearly at right angles to the longitudinal axis of the brain. They 

 do not reach the middle line, because in this region the hippo- 

 campal gyrus emerges from below on to the upper surface of the 

 brain, and becomes continuous anteriorly with the sagittal gyrus. 

 The margins of this eruptive portion of the hippocampal gyrus 

 form with the crucial fissure a Y-shaped furrow on each side, the 

 lines of the Y being widely divergent and forming with each other 

 a'very obtuse angle. The median portion thus enclosed has been 



