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 splint-like 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 digits.  Thus the part of the
     horse’s skeleton which corresponds 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 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 fore foot. 
     And, as in the fore foot, there are merely 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 peculiar 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 least modified mammals, in fact, have the radius and ulna, the tibia and fibula, distinct and separate.  They have five distinct and complete digits on each foot, and no one of these digits is very much larger than the rest.  Moreover, in the least modified mammals, the total