76 THE GEOLOGICAL EVIDENCES 



that of the forms which successively followed 

 them. In some of the Dinocerata, which were 

 by far the largest of the Eocene Mammalia, 

 nearly equalling the elephant in size, the brain 

 was so small that it could have been passed 

 through the neural arches of the lumbar or 



1, Skull of Tinoreras (Uintatherium) ingens, with brain cast in position ; 

 2, of Dinoceras laticeps. Middle Eocene. (After Marsh.) 



