92 Journal of Comparative Neurology. 



13. The insular area, in the more generalized types of 

 mammals, at least, does not belong primarily to the rhinenceph- 

 alon as held by Turner in regard to the human brain. 



14. The fissured surface which is usually the dorsal in the 

 raccoon, the deer, the burro, the horse, the pig, and the sheep, 

 is homologous with what appears on the lateral surface of the 

 insula of the Primates, most of the Carnivora and some others. 



15. The variation in the plane of the fissured surface of 

 the insula is probably due to some peculiarity in the develop- 

 ment of the brain stem. 



16. Fissures on the insula are less deep and more open 

 than on the surrounding parts ; this is probably due to growth 

 under pressure of overlapping parts. 



17. The lack of conformity between the Sylvian and 

 transinsular fissures both in position and direction is probably 

 due to the mechanical effect of growth in an enclosed space by 

 which a displacement of the Sylvian has occurred. 



18. The difference in the relative mass of the insula, its 

 position, plane and relative development in the camel and deer 

 is very much greater than might be expected in two animals so 

 closely related. 



19. The difference between the insula of the bear and the 

 raccoon is very striking. 



20. It is noteworthy that the cat {F. domcstica) and oce- 

 lot {F. pardalis) and the lynx have no insula, while the panther 

 {F. co)icolo7) and the lion [F. Ico) have a rudimentary one. ' 



21. The overlapping of the insula in the human brain, 

 and presumably in others, is not due to a cessation of growth 

 of the insula but to the more rapid growth of the surrounding 

 lobes and the rapid enlargement of the paracceles. 



22. The apparent approximation to a pole in the horse is 

 noteworthy. 



23. The primitive insula, if such exists, is a somewhat 

 elevated area of greater or less size surrounded by a circuminsu- 

 lar fissure and located in the Sylvian fossa or in the fissure if 

 the fissure is continuous with the rhinal. 



