Page:Popular Science Monthly Volume 22.djvu/770

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THE POPULAR SCIENCE MONTHLY.

nourish such bulky bodies; and, the third, good defensive weapons to protect themselves against each other and against their enemies.

PSM V22 D770 Tropical europe of long ago.jpg
Fig. 9.

In the three-toed group of the vegetable-eaters, the horse has the most interesting history. It was in America that the tribe began, for there we find that tiny pony not bigger than a fox, with four horn-covered toes to his front feet (and traces of a fifth), and three toes on his hind ones. Then, as ages went on, we meet with forms with only three toes on all the feet, and a splint in the place of the fourth on the front ones. In the next period they have traveled into Europe, and we find larger animals with only three toes of about equal size. One more step, and we find the middle toe large and long, and covered with a strong hoof, while the two small ones are lifted off the ground. Lastly, in the next forms, the two side-toes became mere splints; and, soon after, well-built animals with true horse's hoofs abounded, the one large hoof covering the strong and broad middle toe. For what we call a horse's knee is really his wrist, and just below it we can still find under the skin those two small splints running down the bone of the hand, while the long middle finger, or toe, with its three joints, forms what we call the foot. It is by these small