AMERICAN ZOOLOGISTS AND EVOLUTION. 195 



tition, embracing large cutting tusks, and altogether forming a beast 

 like the fabled monsters of old. 



A study of its cranial cavity, made by Prof. Marsh, shows that its 

 brain was proportionally smaller than that of any known mammal. 

 Indeed, it was almost reptilian, and of such diminutive size that it 

 could have been drawn through the neural canal of all the presacral 

 vertebrae. Prof. Marsh has followed up this discovery with the most 

 important results, and is now prepared to state the following con- 

 clusions : 



1. That all the Tertiary mammals had small brains. 



2. There is an increase in the size of the brain during this period. 



3. This increase was mainly confined to the cerebral hemispheres 

 or higher portion of the brain. 



4. In some groups the convolutions of the brain have gradually 

 become more complicated. 



5. In some the cerebellum and olfactory lobes have even dimin- 

 ished in size. 



He also finds some evidence that the same general law holds good 

 for birds and reptiles from the Cretaceous to the present time. 1 



Thus we have in other groups as well as man convincing proof 

 that, with successive survival of forms, there is a corresponding sur- 

 vival of larger brains. 



Prof. Shaler 2 has offered some suggestive thoughts in showing 

 the intense selective action which must have taken place in the shape 

 and character of the pelvis in man, on his assumption of the erect 

 position the caudal vertebra? turning inward; the lower portion of 

 the pelvis drawing together to hold the viscera, which had before 

 rested on the elastic abdominal walls ; the attending difficulties of 

 parturition, and other troubles in those parts all pointing to the 

 change which has taken place. 



In this connection Prof. Shaler remarks that the question of labor 

 in woman must not be overlooked from this standpoint. 



In a memoir on the shell-heaps of Florida, by Prof. Wyman, 

 wherein he describes a number of low characters in man already 

 alluded to, he gives the following conclusions : " The steady progress 

 of discovery justifies the inference that man in the earlier periods of 

 his existence, of which we have any knowledge, was at most a savage, 

 enjoying the advantage of a few rude inventions. According to the 

 theory of evolution, which has the merit of being based upon, and not 

 inconsistent with, the observed analogies and processes of Nature, he 

 must have gone through a period, when he was passing out of the 

 animal into the human state, when he was not yet provided with 

 tools of any sort, and when he lived the life of a brute. 



>> 3 



1 American Journal of Science, vol. xii., July, 18*76. 



2 " Proceedings of the Boston Society of Natural History," vol. xv., p. 188. 



3 " Memoirs of the Peabody Academy of Sciences," vol. i., part iv. 



