168 THE STEUCTUEE OF THE HOESE 



hand, which mark the position of the joint between the 

 metacarpal bones and the first phalanges of the digits. 

 Over these, especially when the palm is subject to 

 pressure and friction from hard manual labour, the epi- 

 dermis is somewhat thickened. The sole of the foot 

 presents exactly the same arrangement. In such an 

 animal as a dog or a cat, in which this part of the foot 

 comes to the ground in walking, there is a large trilobed 

 prominent, bare pad (fig. 23, B, 6), composed of a thick 

 fatty cushion, covered with a hardened epidermis, gene- 

 rally of a black colour. There are also smaller pads in 

 front of this on the under surface of each of the toes, 

 but the large one corresponds with the coalesced three 

 middle prominences of the human palm or sole just 

 noticed. 



In the horse's nearest living relatives, the tapir and 

 rhinoceros, the same arrangement holds good. There 

 is a large pad under the forepart of the middle of the 

 foot, which in these animals rests on the ground, and 

 also a hard sole under each toe (see fig. 7, p. 44). Now 

 the ergot of the horse clearly, both by structure and 

 position, corresponds to the palmar or plantar pads of 

 those animals which walk more or less on the palm and 

 sole. Owing to the modified position of the horse's foot, 

 standing only on the end of the last joint of the one 

 toe, this part of the foot no longer comes to the ground, 

 and yet the pad with its bare and thickened epidermic 



