Characteristics of the Horse.

The proof of Evolution cannot be complete until we have obtained evidence of this character, and that evidence has of late years been forthcoming in considerable and continually increasing quantity. Indeed, it is somewhat surprising how large is the quantity of that evidence, and how satisfactory is its nature, if we consider that our obtaining such evidence depends upon the occurrence in that particular locality of an undisturbed series deposited through along period of time, which requires the further condition that each of these deposits should be such that the animal remains imbedded in them arc not much disturbed, and are imbedded in a state of great and perfect preservation. Evidence of this kind, as I have said, has of late years been accumulating largely, and in respect to all divisions of the animal kingdom. But I will select for my present purpose only one particular case, which is more adapted to the object I have in view, as it relates to the origin, to what we may call the pedigree, of one of our most familiar domestic animals—the horse. But I may say that in speaking of the origin of the horse, I shall use that term in a general sense as equivalent to the technical term Equus, and meaning not what you ordinarily understand as such, but also asses, and their modifications, zebras, &c. The horse is in many ways a most remarkable animal, inasmuch as it presents us with an example of one of the most perfect pieces of machinery in the animal kingdom. In fact, among mammals it cannot be said that there is any locomotive so perfectly adapted to its purposes, doing so much work with so small a quantity of fuel as this animal—the horse. And as a necessary consequence of any sort of perfection, of mechanical perfection as of others, you find that the horse is a beautiful creature, one of the most beautiful of all land animals. Look at the perfect balance of its form, and the rhythm and perfection of its action. The locomotive apparatus is, as you are aware, resident in its slender fore and hind-limbs; they are flexible and elastic levers, capable of being moved by very powerful muscles; and in order to supply the engines which work these levers with the force which they expend, the horse is provided with a very perfect feeding apparatus, a very perfect digestive apparatus.

Without attempting to take you very far into the region of osteological detail, I must nevertheless—for this question depends upon the comparison of such details—trouble you with some points respecting the anatomical structure, of the horse, and more especially with those which refer to the structure of its fore and hind limbs. But I shall only touch upon those points which are absolutely essential to the inquiry that at we have at present put. Here (taking a leg-bone of a horse in his hand) is the fore-leg of a horse. The bone which is cut across at this point is that which answers to the upper-arm bone in my arm, what you would call the humerus. This (referring to the bone) corresponds with my fore-arm. What we commonly term the knee of the horse, is the wrist; it answers to the wrist in man. This part of the horse's leg answers to one of the human fingers, and the hoof which covers this extended joint answers to one of my nails.

Now there are certain peculiarities about this structure, bearing relation to further details of the different portions of the human arm to which I have referred. You observe that to all appearance (referring to the horse's leg) there is only one bone in the fore-arm. Nevertheless, at this end r can trace two separate portions; this part of the limb and the one I am now touching. But as I go further down, it runs at the back part into the general bone, and I cease to be able to trace it beyond a certain point. This large bone is what is termed the radius, and answers to the bone I am touching in my arm, and this other portion of bone corresponds to what is called the page 30 ulna. To all appearance, in the fore-arm of the horse the ulna is rudimentary, and seems to be fused into one bone with the radius.

It looks thus, as if the ulna, running off below, came to an end, and it very often happens in works on the anatomy of the horse that you find these facts are referred to, and a horse is said to have an imperfect ulna. But a careful examination shows you that the lower extremity of the ulna is not wanting in the horse. If yon examine a very young horse's limb, you will find that this portion of the bone I am now showing you is separated from the rest, and only unites as the animal becomes older, and this is, in point of fact, the lower extremity of the ulna; so that we may Bay, that in the horse the ulna in the middle part becomes rudimentary, and becomes united with the radius, and se early united with the lower extremity that every trace of separation has vanished.