far our present knowledge leads us, a motive is given to genius by the opportunity created for its exercise. No pains have been spared to investigate the hypotheses which have been made known; they have been candidly put to the test, and on the proof of their inefficiency discarded. That the reader may judge for himself, the tables of teeth, and mouths of various ages are presented. The altered aspect of the tables at the ninth year is indicated in the following wood-cut, which exhibits these surfaces as gaining depth and narrowing from side to side. This appearance they generally assume, and at the same time the infundibula are either lost or much contracted. [Illustration] The next wood-cut, which depicts the form of the tables at the tenth year, though true in its general character, will serve to show how far dependence may be placed in ordinary signs, since the infundibulum of the lateral nipper shows a well-marked cavity, while from the other teeth it seems to be upon the eve of disappearing. On inspection, however, it will be seen that in figures the tables approach more towards the square, which is the last form these surfaces assume. [Illustration] 53. _At twelve years old, there may be tartar on the lower tush. The teeth are longer, narrower, and the enamel darker._ The coloured engraving, which was, on the last occasion justified by a comparison with the mouth of that famous horse, Charles the Twelfth, will convey a general idea of the prevailing characteristics of this age. The teeth have lost the white and firm set aspect they bore at the eighth year. Often, at this period, they have, by wear, become irregular generally, as exhibited in the plate; the grooves, extending down the length of the upper incisors, contain the remnants of the crusta petrosa, which is almost black. The upper tush is usually much diminished, while the lower is long, especially in stallions kept for service. The teeth project more outward and begin to arrange themselves more in a line, no longer showing the crescentic order which they assumed at five years old. Also, by the twelfth year, the tongue, when the jaws are closed, protrudes from the open space between the incisors and molars. The degree in which these alterations have taken place, together with the protrusion of the incisors, is all that is present to guide the judgment; and practical experience is needed, to give him, who attempts to decide upon such weak evidence, any chance of success. As in cases of this description every thing that can help the judgment is eagerly seized upon, the general appearance of the animal is always to be considered; and that may warn the practitioner to modify his opinion. The lower jaw is sharp, the cheeks flat, and around the tushes there may be an accumulation of tartar. It is true the tables, consequent on the wear of the teeth, will have undergone some change, but that alteration is now so slightly marked as not to enforce itself upon the observation.