The Foot of the Horse Considered.

I need not trouble you with the structure of this portion that answers to the wrist, nor with a more full description of the singular peculiarities of the part, because we can do without them for the present, but I will go on to a consideration of the remarkable series of bones which terminates the fore-limb. We have one continuous series in the middle line which terminates in the coffin bone of the horse upon which the weight of the fore-part of the body is supported. The series answers to a finger of my hand, and there are good reasons—perfectly valid and convincing reasons, which I need not stay to trouble you with—which are demonstrative that this answers to the third finger of my hand enormously enlarged.

And it looks at first as if there was only this one finger in the horse's foot. But if I turn the skeleton round, I find on each side a bone shaped like a splint, broad at the upper and narrow at the lower end, one on each side. And those bones are obviously and plainly and can be readily shown to be the rudiments of the bone which I an now touching in my own hand—the metacarpal bones of the second and of the fourth finger—so that we may say that in the horse's fore-limb the radius and ulna are fused together, that the middle part of the ulna is excessively narrow, and that the foot is reduced to the single middle finger, with rudiments of the two other fingers, one on each side of it. Those facts are represented in the diagram I now show you of the recent horse. Here is the fore-limb (pointing to the diagram) with the metacarpal bones and the little splint bones, one on each side. It sometimes happens that by way of a monstrosity you may have an existing horse with one or other of these toes—that is, provided with its terminal joints.

Let me now point out to you what are the characteristics of the hind-limb. This (pointing to the diagram) is the shin-bone of the horse, and it appears at first to constitute the whole of the leg. But there is a little splint at this point (illustrating) which is the rudiment of the small bone of the leg—what is called the fibula—and then there is connected with this great bone a little nodule which represents the lower end of the fibula, in just the same way as that little nodule in the fore-limb represents the lower end of the ulna. So that in the leg we have a modification of the same character as that which exists in the fore-limb—the suppression of the greater part of the small part of the leg and the union of its lower end with the tibra. So, again, we find the same thing if we turn to the remainder of the leg. This (showing) is the heel of the horse, and here is the great median toe, answering to the third toe in our own foot, and here we have upon each side two little splint bones, just as in the fore-limb, which represent the rudiments of the second and fourth toes—rudiments, that is to say, of the metatarsal bones, the remaining bones having altogether vanished. Let me beg your attention to these peculiarities, because I shall have to refer to them by-and-by. The result of this modification is that the fore and hind-limbs are converted into long, solid, springy, elastic levers, which are the great instruments of locomotion of the horse.