78 Journal of Comparative Neurology. 



sented in the seal (yPJioca vihiliiia ) and the panther {^Fclis con- 

 color) in Figs. 9 and lo respectively. In each the area is devoid 

 of fissures except the circuminsular, thus indicating its very rud- 

 imentary character. The area is only slightly elevated and was 

 entire concealed within the Sylvian fissure. It is present and 

 of about the same rudimentary character in the hyena where it 

 is flatter than in the preceding and is entirely concealed. It is 

 concealed and rudimentary in the lion. In 1879 Pansch (45^ 166) 

 said that it is present but concealed in the fox. 



Fig. 1 1 represents this area in the raccoon. The circum- 

 insular fissure is interrupted at two points leaving the insula 

 joined to the temporal lobe caudad and the cephalic boundary 

 ill defined. This elongated and flattened area is crossed by a 

 fissure which is believed to represent the transinsular, although 

 it does not correspond exactly with the direction of the Sylvian 

 (see Fig. 12), as is usually the case in the imprimates at least. 

 Nevertheless it almost completely divides the area into a pre- 

 insula and a postinsula, is deepest at its junction with the rhinal 

 and at that point it corresponds in position with the Sylvian, 

 This lack of conformity is strongly suggestive of a displacement 

 of the Sylvian fissure as the result of growth in an inclosed 

 space which may have carried the dorsal end of the Sylvian 

 eaudad while the bounding parts of the ventral end, which is 

 more closely connected with the brain stem, have maintained 

 their original position. Future investigation may also show that 

 some peculiar development of the frontal or parietal lobes or of 

 both has aided in bringing about this condition. The relation 

 of the transinsular to the Sylvian fissure in this brain is strik- 

 ingly similar to that in the human, but in the raccoon there is 

 no evidence of the central fissure. The area is otherwise un- 

 fissured, but slightly elevated and, with the exception of the 

 cephalic third which lies concealed in the Sylvian fossa, it is 

 completely hidden within the lips of the Sylvian fissure. As 

 previously stated, the cephalic boundary is ill defined and the 

 insular area graduates out into the frontal lobe as in the case of 

 young pigs. The plane (plane of fissured surface) of the insula 

 in this specimen forms an angle of more than 45° to the lateral 



