282 COMMON BUITISH ANIMALS 



a three-toed horse was ruiiiiiiig in the streets of 

 London in a butcher^s cart not many years ago. 

 'J'he remains of three-toed horses are found in the 

 Pliocene of Europe, Asia, North Africa, and America, 

 and specimens have been discovered of the three- 

 toed horse Hipparion in the English Red Crag. The 

 side toes of these horses were diminutive and did not 

 touch the ground, like the petti-toes of the pig. 

 The horse of the present day is a larger animal than 

 its ancestors ; the links in the chain gradually become 

 smaller and smaller, as they are more remote. 



In the Miocene and Oligocene both of Europe and 

 America horses are found of smaller size than the 

 Pliocene horses with longer side toes, Avhich would 

 have reached the ground and been functional. The 

 teeth, however, of these animals are not so highly 

 specialised. They serve to connect the Pliocene 

 three-toed horses with the lower Eocene Hyraco- 

 therium, an animal found in the London Basin, about 

 the size of a fox with a separate ulna, and four 

 spreading toes on the fore-foot and three on the 

 hind foot. At a still earlier period at the base of 

 the Eocene both of Europe and America is found a 

 small five-toed animal, Phenacodus, which may be 

 regarded as the ancestor not only of the horses, but 

 of all the Ungulates. 



The American series, which has been worked out 

 by Prof. Osborn, is more complete than the Old 

 World series, because the old world three-toed horse, 

 Hipparion, is not considered to be on the direct line, 

 by reason of its larger size and other specialisations. 

 We have, therefore, still to find an Old World link 



