THE TRIUMPH OF THE MAMMALS loi 



from the grim struggle on land, the carnivores are 

 now mainly divided into a "dog" family and a "cat" 

 family. We have the common ancestors of these, 

 and can satisfactorily trace the evolution : the bears, 

 dogs, wolves, foxes, otters, jackals, badgers, etc., on 

 the one hand, and the lion, tiger, leopard, lynx, 

 hy^na, mongoose, etc., on the other. In the early 

 period we have carnivores with the general features 

 of the various types in one body, and, slowly, in the 

 course of two or three million years, the specific 

 types are shaped. There were at an early date even 

 fiiercer carnivores than now. At one time there was 

 a large lion-tiger (the "Sabre-Toothed Tiger," it is 

 often called), with canine teeth, of terrible strength, 

 seven or eight inches long. 



These carnivores I take first because they help us 

 to understand the rest of the mammal family. They 

 proved to be the customary grisly machinery of 

 natural selection. Largely in the attempt to get 

 away from them, as well as to avoid competition for 

 food, the rest of our mammals spread in all directions. 

 Moles and rabbits found refuge underground. Hedge- 

 hogs and porcupines developed their barbed-wire 

 entanglements. Squirrels remained in the trees and 

 obtained their great agility. Shrews took to the 

 streams; porpoises and whales to the sea. Some 

 (lemurs, bats, etc.) adopted night life, instead of day 

 life. Some of the carnivores did the same, and new 

 and more wonderful devices had to be evolved. 



