Paleontological Discovery. 857 
The extinct Marsupials of Australia, and the Edentates of 
outh America, are well known examples. The Pliocene hip- 
popotami of Asia and the South of Europe point directly to 
migrations from Africa. Other similar examples are numerous. 
The fossil plants of the Arctic region prove the existence of a 
climate there far milder than at present, and recent researches 
at least render more probable the s stion, made me ago by 
Buffon, in his “Epochs of N tare? Ge life b in t 
regions, and by successive migrations from them the conti- 
nents were peopled. 
One of the important results of recent paleontological 
research, is the law of brain-growth, found to exist amon. 
extinct mamm , and to some extent in other vertebrates. 
According to this law, as I have briefly stated it elsewhere: 
“All Tertiary mammals had small brains. There was, also, a 
oe increase in the size of the brain during this period. 
shed in size.” More recent researches render it probable 
that the same general law of brain-growth holds good an birds 
_ and reptiles from the Mesozoic to the present time. 
