ITS ANCESTORS AND RELATIONS. 19 



to light. How do we not know that the next ten or 

 twenty years may not be equally fruitful in new dis- 

 covery ? 



After giving a summary of what was then known 

 of the ancestry of the horse, as disclosed by pala3on- 

 tological evidence, Professor Huxley wrote in 1877 :* 

 " 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 epoch 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 in- 

 nermost or first digit in front, with probably a rudi- 

 ment 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 ani- 

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

 founded, the whole series must have taken origin." 



This anticipation has been completely verified by 

 the discovery, among others, of Phenacodus in the 

 Wasatch beds, which there is every reason to believe 

 are nearly, if not quite, the oldest of the Eocene for- 

 mations of North America. 



Although this most interesting animal was known 

 and named by Cope as long ago as 1873 from teeth 

 alone, it was not until the more recent discov- 

 * American Addresses : Lectures on Evolution, p. 89. 



