48 



ANIMAL LOCOMOTION. 



extremities of the toes superiorly are armed with powerful 

 short nails, the tips of which project inferiorly to protect the 

 toes and confer elasticity when the foot is leaving the ground. 

 The foot like the leg, is remarkable for its great strength. 

 The legs of the ostrich are closely set, another feature of 

 speed.^ The wings of the ostrich are in a very rudimentai y 



Fig. 25.— Ostnehes pursued by a Hunter. 



condition as compared, with the legs.^ All the bones are pre- 

 sent, but they are so dwarfed that they are useless as organs 

 of flight. The angles which the bones of the wing make with 

 each other, are still less than the angles made by the bones ot* 

 the leg. This is just what we would a priori expect, as the 

 velocity with which wings are moved greatly exceeds that 

 with which legs are moved. The bones of the wing of the 

 ostrich are inclined towards each other at nearly right angles. 



1 In dranght horses the legs are much wider apart than in racers ; the legs 

 of the deer being less widely set than those of the racer. 



2 In the apteryx the wings are so very small that the bird is commonl;y 

 spoken of as the wmgless bird." 



