THE UNGULATA, OE HOOFED ANIMALS. 129 



the struggle for existence. The case is this : the 

 original five-toed extremity (compare above Fig. 1, 

 p. 36) has, in the second row of tarsals, one bone 

 for every toe. If the side toes become reduced, 

 one of two cases may then happen to the bones of 

 the second row : either 

 they become reduced 

 with the toe, or they 

 are retained for the 

 remaining toe ; i.e. 

 they adapt themselves 

 to the circumstances 

 of the limb which 

 changes with the toes 

 and add to its strength 

 and agility. The ex- 

 amples adduced by 

 Kowalewsky are, in 

 fact, very instructive. 

 In the case of the 

 Eocene Anoploiherium (Fig. 11), the first digit is 

 wanting up to the carpals, but the carpal bone 

 (1) belonging to it exists, only it is reduced and 

 is of no further use. Of the second digit the 

 shortened metacarpal (n) exists, as also the carpal 

 (2), but both are useless. 

 13 



FIG. 11. Left Fore-foot of the 

 Anoplotherium. After Kowa- 

 lewsky. 



