REPORT ON THE SEALS. 119 



convolution was very narrow, and the suprasplenial convolution and fissure were absent, 

 though it is possible that this convolution was potentially present in the callosal con- 

 volution. The crucial fissure was 17 mm. long, and enclosed by a broad sigmoid gyrus 

 which was continuous by its posterior limb with the marginal gyrus. The coronal fissure 

 which bounded it was prolonged backwards into the 1st curved fissure, but not forwards 

 into the praesylvian fissure. Well-defined Sylvian and suprasylvian convolutions were 

 present, but only a slight indication of a division of the marginal convolution into 

 sagittal and mediolateral convolutions was visible. No arched convolution was con- 

 cealed within the Sylvian fissure. The olfactory apparatus was large. 



My dissection of the inner and tentorial surface of the hemisphere of the Otter (Lutra 

 vulgaris) closely accords with Paul Broca's figures and description. 1 In this animal the 

 crucial fissure was 14 mm. long; the sigmoid gyrus was relatively large; the coronal 

 fissure was not continuous with the prsesylvian fissure ; Sylvian, suprasylvian, and mar- 

 ginal convolutions were present ; the anterior limb of the Sylvian was almost entirely 

 concealed in the fissure, and there was evidence of separation of the marginal convolution 

 into sagittal and mediolateral by a short mediolateral fissure which was interrupted ; but 

 the coronal fissure should be regarded as prolonged into the fissure bounding the 

 upper aspect of the suprasylvian convolution, which may therefore be termed lateral. 



In the Coati (Nasua rufa) the postrhinal was separated from the splenial fissure by a 

 short retrolimbic gyrus ; the splenial did not join the crucial fissure, but terminated 

 behind it in a sulcus in the sagittal convolution, which did not reach the margin of the 

 hemisphere. The marginal part of the sagittal convolution was relatively wider than 

 in the Otter and Eatel. The crucial fissure was distinct, but owing to an injury to this 

 part of the brain, I could not speak with certainty of the presence of a prsecrueiate 

 fissure leading forwards and inwards from the crucial fissure ; a small convolution in 

 front of the crucial fissure apparently represented the ursine lozenge, a convolution 

 which Mivart also considers to exist in the brain of this animal. Only three tiers of 

 convolutions were present. 



In the Weasel (Mustela vulgaris) the postrhinal fissure was separated from the 

 splenial by a retrolimbic gyrus which was broad in relation to the size of the hemisphere. 

 The splenial fissure ended in the crucial fissure on the dorsum of the hemisphere. 

 No prascruciate fissure was visible on the dorsum, but on opening up the crucial fissure 

 a very short sulcus indented the convolution which formed the boundary of the crucial 

 fissure and marked off the anterior boundary of a minute ursine lozenge. In the Ferret 

 (Mustela furo) , however, a short but distinct praacruciate fissure differentiated the anterior 

 boundary of a minute ursine lozenge. The splenial fissure ended in the crucial fissure on 

 the dorsum of the hemisphere. The splenial was separated behind from the postrhinal 



1 Figures of the ursine lozenge in the brains of Ursus maritimns and Mcllivora indica have been given by St. George 

 Mivart in his memoir already quoted, and its presence in the brains of the Otter, Badger, Coati, and other Arctoid 

 Carnivora is described by him. 



