124 LECTURES ON EVOLUTION m 



little functional importance, and they must have 

 been rather of the nature of the dew-claws, such 

 as are to be found in many ruminant animals. 

 The Hipparion, as the extinct European three- 

 toed horse is called, in fact, presents a foot similar 

 to that of the American Protohippus (Fig. 9), 

 except that, in the Hipparion, the smaller digits 

 are situated farther back, and are of smaller pro- 

 portional size, than in the Protohippus. 



The ulna is slightly more distinct than in the 

 horse ; and the whole length of it, as a very 

 slender shaft, intimately united with the radius, 

 is completely traceable. The fibula appears to 

 be in the same condition as in the horse. The 

 teeth of the Hipparion are essentially similar 

 to those of the horse, but the pattern of the 

 grinders is in some respects a little more com- 

 plex, and there is a depression on the face of 

 the skull in front of the orbit, which is not seen 

 in existing horses. 



In the earlier Miocene, and perhaps the later 

 Eocene deposits of some parts of Europe, another 

 extinct animal has been discovered, which Cuvier, 

 who first described some fragments of it, con- 

 sidered to be a Palceotherium. But as further 

 discoveries threw new light upon its structure, 

 it was recognised as a distinct genus, under the 

 name of Anchitherium. 



In its general characters, the skeleton of Anchi- 

 therium is very similar to that of the horse. In 



