xiii THE GEOLOGICAL EVIDENCES OF EVOLUTION 385 



what lies below the horse's ' knee ' thus corresponds to the 

 middle finger in ourselves, what has become of the four other 

 fingers or digits ? We find in the places of the second and 

 fourth digits only two slender splintlike bones, about two- 

 thirds as long as the cannon bone, which gradually taper to 

 their lower ends and bear no finger joints, or, as they are 

 termed, phalanges. Sometimes, small bony or gristly nodules 

 are to be found at the bases of these two metacarpal splints, 

 and it is probable that these represent rudiments of the first 

 and fifth toes. Thus, the part of the horse's skeleton which 

 corresponds with that of the human hand, contains one over- 

 grown middle digit, and at least two imperfect lateral digits ; 

 and these answer, respectively, to the third, the second, and 

 the fourth fingers in man. 



" Corresponding modifications are found in the hind limb. 

 In ourselves, and in most quadrupeds, the leg contains two 

 distinct bones, a large bone, the tibia, and a smaller and more 

 slender bone, the fibula. But, in the horse, the fibula seems, 

 at first, to be reduced to its upper end ; a short slender bone 

 united with the tibia, and ending in a point below, occupying 

 its place. Examination of the lower end of a young foal's 

 shin-bone, however, shows a distinct portion of osseous matter 

 which is the lower end of the fibula ; so that the, apparently 

 single, lower end of the shin-bone is really made up of the 

 coalesced ends of the tibia and fibula, just as the, apparently 

 single, lower end of the forearm bone is composed of the coal- 

 esced radius and ulna. 



" The heel of the horse is the part commonly known as 

 the hock. The hinder cannon bone answers to the middle 

 metatarsal bone of the human foot, the pastern, coronary, 

 and coffin bones, to the middle toe bones ; the hind hoof to 

 the nail ; as in the forefoot. And, as in the forefoot, there 

 are merely two splints to represent the second and the fourth 

 toes. Sometimes a rudiment of a fifth toe appears to be 

 traceable. 



" The teeth of a horse are not less peculiar than its limbs. 

 The living engine, like all others, must be well stoked if it is 

 to do its work ■ and the horse, if it is to make good its wear 

 and tear, and to exert the enormous amount of force required 

 for its propulsion, must be well and rapidly fed. To this end, 



2 c 



