The needs which led, in a slow accumulative way, to the invention of the admirable contrivance of the horse's foot, were doubtless founded on the necessities of swift movement in fleeing from the great predaceous animals. Incidentally, however, as this development has gone on, the peculiarities of the extremity have proved highly advantageous in defence, and the creatures have acquired certain peculiar ways of using their feet effectively to this end. The solid character of the hoof, its considerable weight, and the great power of the muscles of the hams, which are the principal agents in propelling the animal, make the hind feet capable of delivering a very powerful blow. The measure of its efficiency may be judged from the fact that a lion has been slain by a stroke from the foot of a donkey, and in their wild state a herd of horses with their heads together, can beat off the attack of the most powerful beasts of prey. In using the hind feet for assault or defence, horses have adopted an effective method of kicking which is unknown among other animals. Resting on their fore-legs, the hinder feet are thrown backward and upward, so that they may strike a blow six feet from the ground. Many of our cloven-footed animals have learned to strike cutting blows with the sharp hoofs of their fore-limbs--our bulls will stamp a fallen enemy with great force; but the backward kick of the horse is a peculiar movement, and is distinctly related to the peculiar structure of the animal's extremities. It is an interesting fact that the development of a long and slowly elaborated series leading to the making of the horse appears to have taken place mainly, if not altogether, in the region about the headwaters of the Missouri River. In the olden days when this great work was done, that part of our continent was a well-watered country, much of its surface being occupied by great lakes which have long since disappeared. In the deposits accumulated in these bodies of fresh water are found the bones of the olden species telling the history of their series. It is not yet certain that the final step of the accomplishment which gave us our existing species was effected in this land. It seems indeed most likely that the ancestral form of our domesticated horses found their way to the continents of the Old World, and there underwent the last slight changes, before they were made captive by man. If there ever were perfect horses on this continent, they had passed away from its area before the coming of man to the land. The history of our aborigines would have been quite other than it has been, if they had had a chance to win the assistance of this noble helpmeet.