MODERN SCIENCE. 135 



ascend to remote ancestors, and establish the genealogy of 

 many species. Up to the present day, " We have attained," 

 says Prof. Cope, one of our highest authorities on the 

 subject, " the long since extinct ancestor of the lowest ver- 

 tebrates; we have the ancestors of all the reptiles, of the 

 birds, and of the mammals. And if we consider mammals 

 separately, we have traced up a great many lines to their 

 points of departure from very primitive types. Thus we 

 have obtained the GENEALOGICAL TREE of 



the deer, camel, musk, 



horse, tapir, rhinoceros, 



cats, dogs, lemurs, 



monkeys, and have important evidence as to 

 the origin of man." And the significance of this fact is 

 much increased by the details of the FILIATION in the 

 course of development. Taking, for instance, THE HORSE 

 as we have it at present, we find that its earliest family 

 ancestor (in America) was : 



In the Early Eocene (Tertiary Period), the EOHIPPUS, the 

 size of a fox, with four toes and the remnant of one fifth toe ; 



Then in the Upper Eocene, the OROHIPPUS, whose rudimen- 

 tary first toe was gone and the fifth toe was reduced to a splint ; 



Then in the Lower Miocene, the MISOHIPPUS, the size of 

 a sheep, with a rudimentary splint on the foreleg and only 

 three toes ; 



In the Upper Miocene came the MIOHIPPUS, who comes 

 near the Anchitherium of Europe the tips of whose outer 

 toes just touched the ground ; * 



In the Lower Pliocene, the PROTOHIPPUS, the size of an 

 ass, nearly similar to the Hipparion of Europe three toes 

 only, the middle of which only touched the ground ; 



In the Middle Pliocene, the PLIOHIPPUS, who has lost 

 the small hooflets on the rudimentary toes in all aspects 

 resembling the horse ; 



In the Upper Pliocene finally came the HORSE, with one 

 solid toe covered with a single solid nail (the hoof). 



In Europe, the earliest ancestor of the horse as yet found 

 was the PAL^EOTHERIUM, with three toes, the middle one 

 being the largest ; 



