Horses' teeth are so important a part of their history, that although this book does not profess to treat of science, it would be incomplete if I did not briefly point out how distinctly they shew the age of the animal. First of all, however, it should be known, that the mouth seems to have been expressly formed for the bit, by which man controls this admirable creature; for, corresponding with each angle of the mouth is a space between the teeth, in which it lodges with the greatest convenience. The front teeth, or incisors, begin to appear when the horse is fifteen days old, and amount to six in number in each jaw. All, from the first, are at the top, or crown, hollowed into a groove. The two in the middle are shed and replaced at three years and a half, the two next at four and a half, and the two outside, called the corner teeth, at seven and a half, or eight. The grooves on the crowns, become effaced, and the tops of the teeth are more triangular as age increases. The females have no canine teeth; but the males always have two small ones in the upper jaw, and sometimes two in the lower; the former appear when they are four years old, the latter at three and a half; they remain pointed till the horse has attained six years, and when he is ten they begin to grow loose, and expose their roots. They have six grinders in each side of each jaw, with flat crowns, and the plates of enamel which surround the dental substance, appear in them like four crescents. The life of horses generally lasts about thirty years; but they have frequently been known to exceed that age. Then, however, mastication has become difficult, they get lean, or what is called out of condition; and old favorites, if they are attended to as they ought to be, after long and faithful services, have their food bruised, and even cooked for them. It is surprising to see what entire rest frequently does for them, even at an advanced age; and I have seen them, in consequence of it, again taken into a degree of service when they have been supposed past all work.