68 MIGHTY ANIMAL^ 



disappeared. But other species which were more 

 fortunate lived through these changes, although, 

 in doing so, their whole manner of life was altered 

 and also their forms. When some of the land ani- 

 mals could no longer get enough to eat on the 

 land, they found food in the water and, after many 

 generations, became water animals. Some of the 

 ancestors of the Ichthyosaur were probably thus 

 driven from the land to keep themselves from 

 starvation. This was what happened to the ances- 

 tors of the whale and seal of to-day, for these 

 creatures are descended from land animals. But 

 it took centuries upon centuries for land animals to 

 become so adapted to the water that they could 

 live in it entirely. 



When in the full glory of their power, the Ich- 

 thyosaurs swarmed in the waters of Europe, India, 

 Australia, New Zealand, and the east coast of 

 Africa ; but they were not so numerous in America. 

 Yet, mighty as they were, they did not maintain 

 their position as rulers of all these waters without 

 some trouble; for they had many dangerous en- 

 emies, among which were the Plesiosaurs. 



