198 THE POPULAR SCIENCE MONTHLY. 



their ornamental manes and their proud and stately gait and car- 

 riage. All these points are wholly wanting in the clumsy llama 

 and alpaca group. Stranded remnants, as it were, of the Eocene 

 world, those antique creatures linger on among their mountain 

 valleys a perpetual milestone by whose indications we may mark 

 the progress since effected, under stress of selective agencies, in 

 the main advancing body of the higher ruminants. 



On such a simple original type, defenseless and ungainly, the 

 camel is a specialized and adapted desert variation. The unde- 

 veloped llamas have no humps, and they have their two toes quite 

 separated in a certain awkward, ungraceful, splay-footed fashion. 

 In the true camels, on the other hand, the two toes are united 

 below by a kind of horny sole, almost to their points, which ter- 

 minate in a couple of small hoofs, and beneath the foot there is a 

 soft cushion, by which the instep bears upon the sandy soil over 

 whose expanses the creature is adapted to move. This padded 

 sole is to the camel what the solid hoof is to the horse, it fits him 

 exactly for the sort of ground over which his ancestors have 

 stalked and shambled for countless generations. And it is inter- 

 esting to note the similarities and differences which natural selec- 

 tion has brought about in the case of these two chief human 

 beasts of burden. 



In both the foot has become adapted for scouring the open 

 plain only; firmness and sureness of tread have been the sole 

 qualities that really told, and hence, in both, the toes as such 

 have become practically extinct, and in their place one gets at 

 last a single united broad-based foot, such as gives the animal 

 the most secure foundation for his heavy body upon the level 

 ground. 



Compare for a moment these two types of practically toeless 

 foot with the grasping hand of the forestine monkeys, the sharp 

 claws of the tree-haunting squirrels, the light paw of the leaping 

 hare, or even the slender and delicate ungulate feet of the gazelles 

 ajid the chamois, and you will see how wholly they have been 

 specialized for their work as trotters only. In the ruminants gen- 

 erally, as in all the great division of hoofed mammals, the extrem- 

 ities are calculated for support alone ; but in the horse and in the 

 camel this restriction of function reaches its highest practical 

 point, and the feet and legs exist merely as adequate and extreme- 

 ly stable props for the heavy framework. In the horse the solid 

 hoof remains as the sole surviving toe out of the original five pos- 

 sessed by his primitive ancestors in the American Eocene (though 

 the "splint-bones," well known to the veterinaries, are the last 

 f unctionless relics of two other toes) ; in the camel the same result 

 is practically attained by the union of the two toes which it still 

 possesses through the medium of a single horny sole, as well as by 



