45. _At four years, four pairs of horse teeth are well up, but the corner milk teeth are retained._ Such a state of the mouth is very characteristic of the age, and not likely to be mistaken. The appearance which the teeth present, if viewed from the front when the lips are separated, is shown in the coloured engraving, and it is such as no person can well mistake. The original drawing in this case was also made for the Jockey Club, and was produced upon the famous trial. On all occasions that presented themselves, which have indeed been numerous, it has been compared with the mouths of living animals, and in no single instance has it been found to be contradicted. This has not only been done with colts, but also with fillies, among which last I may mention Lupine, Mora, Nightcap, Chamois, and Jew Girl. To the plate, therefore, the reader should refer; and supposing him to have done so, the other indications which the mouth presents between the third and fourth year will now be enlarged upon. The state of the molars at this period may be regarded as demonstrative of the age of the animal. The reader will remember, that according to what has been pointed out, the colt at three years old has five molar teeth on either side of both jaws, and that of these teeth, one only, the third in situation, marked thus, 4* in the frontispiece, is of a temporary nature. Shortly after the upper lateral milk incisors have been cast off, and sometimes previous to that occurrence, the point of the sixth molar penetrates through the gum, and before it is fully up the covering of the third permanent molar is removed. This effected, the colt has six molars on either side of both jaws, and whenever that number is found they may be assumed to be all of a permanent character; so at four years old the tables of the central incisors exhibit some considerable wear, the infundibula no longer extend entirely across, but have become circumscribed and well defined. The tables of the lateral incisors, on the contrary, are only beginning to be formed, and very often the part posterior to the infundibulum has not received any attrition. The infundibula in these last extend the entire breadth of the table, and in consequence of an indentation on that side which touches the corner milk teeth, the space is there free. The reader will comprehend this particular formation, by referring to the wood-cut of the table of the tooth presented at page 79, the appearance being so much alike as not to necessitate a repetition to enforce it. When the fourth year, however, has been for a month or two perfected, the tables then assume the form represented in the following wood-cut, which exhibits the change that has taken place in the central incisor, and also the appearance of the more recent lateral tooth when the colt is fairly four years off. [Illustration]