EVOLUTION OF THE ELEPHANT LULL. 



643 



The special adaptations are, as in the horses, primarily for food- 

 getting and locomotion, although incidentally the elephants have 

 developed admirable weapons for defense, which, together with the 

 great size and thick skin, render them almost impregnable to their 

 enemies of the brute creation. 



ADAPTATIONS OF THE LIMBS AND FEET. 



The development of the pillar-like limb of the elephant has been 

 shown to be merely a device to support the enormous bodily weight 

 and was independently acquired in other groups of land animals 



A:;' 



Fig. 2. — Conies, Hyrax abyssinicits ; after Brehm. 



of huge size. In most quadrupeds, however, the knee and elbow are 

 permanently bent, the upper limb bones being of the shape of an 

 elongated S. Increasing weight necessitates a straightening of the 

 limb in order that the weight may be transmitted through a vertical 

 shaft. This is more far-reaching than one would suppose, as it 

 implies also a straightening of the bones themselves and a shifting 

 of the articular facets from an oblique to a right angle with reference 

 to the long axis of the bone. The foot has changed its posture from 

 the primitive plantigrade position, for the heel and wrist bones are 

 elevated above the ground and a thick pad of gristle has developed 

 beneath them in each foot, forming a cushion to receive a share of 



