THE DOOILE MAMMALS. 



253 



front in four toes and behind in three, and these toes end 

 in hoofs which spread out; a useful feature, since the tapirs, 

 when alarmed, take refuge in swamps and streams. 



On the other hand, the horse has a graceful form, all its 

 lines indicating capacity for great speed, particularly as 

 regards the feet. Here, so to speak, everjrthing has been 

 sacrificed to a single object, i.e., speed. To this end the 

 first, second, fourth, and fifth toes have been abandoned. 



Fio. 261.— Skeleton of Wild Ass. i. incisor teeth ; g, grinding teeth, with the gap 

 between the two sets, as in all large grass-feeders; fc, knee; h, heel; /, foot; 1, 

 S, 3, three joints of the middle toe; «, splint, or remains of one of the two lost 

 toes; e, elbow; w, wrist; ha, hand-bone. 



and the leg is supported on the third toe alone, that cor- 

 responding to our middle finger. Where else shall we find 

 among the mammals such a special adaptation of structure 

 to the needs of the creature? On the other hand, the tapir 

 is what naturalists call a "generalized "form; all the parts 

 of the body being equally developed, just as among man- 

 kind we have jacks-of-all trades, while as examples of spe- 

 cialized types are the geniuses who, as poets, artists, or 

 philosophers, do one thing remarkably well. 



The horse was preceded in geological history by a long 



