IN MODERN SCIENCE. 12/ 



of facts are essentially -different ; and though it 

 is possible to point out in the newer geological 

 formations some genera and species allied to 

 others which have preceded them, and to sup- 

 pose that the later forms proceeded from the 

 earlier, still, when the connecting-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 ». ise which has often been paraded 

 as an illustration of evolution — ♦■he supposed 

 genealogy of the horse. In America a series 

 of horse-like animals has been selected, begin- 

 ning with the Orohippus of the Eocene, 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. 

 Yet this is purely arbitrary, and dependent mere- 

 ly on a succession of genera more and more 

 closely resembling the modern horse being pro- 

 curable 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 PalcBotheriuin — an en- 

 tirely different form — by just as likely indica- 



