72 Thomas Hc^nry Huxley 



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 digits. Thus the part of the horse's skeleton which corre- 

 sponds with that of the human hand contains one overgrown 

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

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

 fourth digits 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, shews 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 fore-arm bone is composed of the 

 coalesced radius and ulna. 



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

 hock ; the hinder cannon bone answers to the middle metatar- 

 sal 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 fore foot. And, as in the fore foot, there are merelv two 

 splints to represent the second and fourth toes. Sometimes a 

 rudiment of a fifth toe appears to be traceable." 



Having in the same fashion described the highly 

 complicated and pectiliar structure of the teeth of 

 modern horses, Huxley proceeded : 



"To anyone who is acquainted with the morphology of 

 vertebrated animals, these characteristic structures of the horse 

 show that it deviates widely from the general structure of 

 mammals ; and that the horse type is, in many respects, an 

 extreme modification of the general mammalian plan. The 



