212 LIFE OF PROFESSOR HUXLEY CHAP. VIII 



telling instances in considerable detail, the one show- 

 ing how the gulf between two such apparently distinct 

 groups as Birds and Reptiles is bridged over by 

 ancient fossils intermediate in form ; the other illus- 

 trating from Professor Marsh's new collections the 

 lineal descent of the specialised Horse from the more 

 general type of quadruped. 



The farthest back of these was a creature with 

 four toes on the front limb and three on the hind 

 limb. Judging from the completeness of the series 

 or forms so far, he ventured to indulge in a prophecy. 



Thus, thanks to these important researches, it has 

 become evident that, so far as our present knowledge 

 extends, the history of the horse-type is exactly and pre- 

 cisely that which could nave been predicted from a 

 knowledge of the principles of evolution. And the 

 knowledge we now possess justifies us completely in the 

 anticipation that when the still lower Eocene deposits, 

 and those which belong to the Cretaceous epoch, have 

 yielded up their remains of ancestral equine animals, we 

 shall find, first, a form with four complete toes and a 

 rudiment of the innermost or first digit in front, with, 

 probably, a rudiment of the fifth digit in the hind foot ; 

 while, in still older forms, the series of the digits will be 

 more and more complete, until we come to the five-toed 

 animals, in which, if the doctrine of evolution is well 

 founded, the whole series must have taken its origin. 



Seldom has prophecy been sooner fulfilled. 

 Within two months, Professor Marsh had discovered 

 a new genus of equine mammals, Eohippus, from the 

 lowest Eocene deposits of the West, which corresponds 

 very nearly to the description given above. 



