THE DISCOVERER 83 



The knowledge we now possess justifies us com- 

 pletely in the anticipation that, when the still lower 

 Eocene deposits, and those which belong to the Cre- 

 taceous period, have yielded up their remains of an- 

 cestral equine animals, we shall find, first, a form with 

 four complete toes and a rudiment of the fifth digit 

 in the hind foot ; while, in the older forms, the series 

 of 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. 1 



The prophecy was fulfilled two months afterwards in 

 Professor Marsh's discovery of complete skeletons of 

 a five-toed animal in the early Eocene deposits at 

 Wasatch in North America. The existence of the 

 fossil form, which is named Phenacodus, was known 

 to Professor Cope three years before by its teeth alone. 

 The unearthing of it, with all the bones in due place, 

 the terminal bones of the toes showing that they were 

 encased in hoofs, enabled palaeontologists to assign it 

 a place in the ungulate group, the type, as shown by 

 the size of the brain-pan, being extremely low. 

 "This," remarks Sir W. H. Flower, " is exactly in 

 accord with what is now generally known of the pro- 

 gressive diminution of the size of the brain in all 

 groups of animals the farther back we pass from the 

 present time." 2 



Reference has been made already to the famous 



1 American Addresses, p. 89. 2 The Horse, p. 22. 



