APPARITION OF SPECIES 109 



possible to point out in the newer geological forma 

 tions some genera and species allied to others which 

 have preceded them, and to suppose that the later 

 forms proceeded from the earlier, still, as the con 

 necting links cannot be found, this is mere supposition, 

 not scientific certainty. Further, it proceeds on the 

 principle of arbitrary choice of certain forms out of 

 many, without any evidence of genetic connection. 



The worthlessness of such derivation is well shown 

 in a case which has often been paraded as an illustra 

 tion of evolution the supposed genealogy of the 

 horse. In America a series of horse-like animals has 

 been selected, beginning with the EoJiippus of the 

 Eocene an animal the size of a fox, and with four 

 toes in front and three behind and these have been 

 marshalled as the ancestors of the fossil horses of 

 America ; for there are no native horses in America 

 in the modern period, the result of the long series 

 of improvements having apparently been extinction. 

 Yet all this is purely arbitrary, and dependent 

 merely on a succession of genera more and more 

 closely resembling the modern horse being procur 

 able from successive Tertiary deposits often widely 

 separated in time and place. In Europe, on the 

 other hand, the ancestry of the horse has been traced 

 back to PalceotJierium an entirely different form 

 by just as likely indications, the truth being that as 

 the group to which the horse belongs culminated in 

 the early Tertiary times, the animal has too many 



