254 WALKS AND TALKS. 



name Mcn-is-co-es'-sus. This also, is similar to the Old 

 World forms. 



Thus all the intimations show that while the mammalian 

 type had already made great advance in the Mesozoic ^Eon 

 almost equally advanced at the beginning and end it was 

 still but meagerly developed. Its affinities, even to the 

 end of the Mesozoic, were with the lower division of mam- 

 mals, the Marsupials. With so little progress between the 

 Triassic and the end of the Cretaceous, we are reminded 

 again, that a long interval of mammalian existence must 

 have passed, before the Triassic Dromaifierium took its place in 

 the world. 



With the opening of Csenozoic time all is changed. The 

 transition reminds us of that from the Eozoic to the Palae- 

 ozoic. The world is now astir with mammalian life; and 

 mammalian life has already attained considerable development 

 in rank and diversification of type. When was this advance 

 effected? Probably during the Cretaceous. Then we must 

 admit that the sole Cretaceous mammal known fails to represent 

 the average of the Cretaceous. But a glance over the assem- 

 blage of early Tertiary mammals at once shows them stamped 

 with inferior characteristics. They are all greatly generalized 

 that is, some characters of two, three, or more of our modem 

 orders are blended in one individual. This principle is ex- 

 emplified in the early representatives of every group of 

 animals. In the next place, they possessed small brains. If 

 we compare one of them with its nearest relative in any later 

 age, and especially with a modern mammal, the disparity in 

 brain is striking. Enlargement of brain is a strong mark of 

 advancement. Another circumstance is the generally penta- 

 dactyl character of these mammals. To have five toes on cadi 

 foot may be thought a mark of superiority, since man has 

 five. But five is the typical or fundamental number. This 

 is possessed by many reptiles and by most of the lowest mam- 

 mals. Advance has been marked by modifications, and these 

 as a fact, have involved, in most cases, a reduction in the 

 number of digits. The extremities of man may, therefore, be 



