EXTINCT ANIMALS 



with those of recent rhinoceros, hippopotamus 

 and horse (Fig. 106), and it is found that although 

 Dinoceras and Titanotherium were bigger 

 than the largest rhinoceros of to-day, yet they 

 had quite small brains, not more than an 

 eighth the volume of that of the recent big 

 animals. The subject has not been so fully 



Fig. 106. — Photographs of plaster casts of the brain-cavity of 

 A, Dinoceras ; B, Hippopotamus ; C, Horse ; and Z>, 

 Rhinoceros : to show the relatively very small size of 

 the brain of Dinoceras. 



looked into yet as it deserves, but it seems that 

 modern animals, the animals which have sur- 

 vived, have much bigger brains than those 

 which died out in the Eocene and Miocene 

 times, and it is probable that they have survived 

 to a large extent because of the value to them, 

 in the struggle for existence, of the bigger brain. 



150 



I 



