56. At thirty years old, the jaws are contracted; the lower are not seen when the upper teeth are in view. The coloured engraving, which at first sight seems to suggest that the animal possessed only a single jaw, exhibits the mouth as it appears at the thirtieth year. The animal, the mouth of which is here depicted, had a lower jaw with excellent teeth considering its age, but without elevating its head these could not, while the mouth was closed, be seen, or when seen, the view of those in the upper jaw was lost. This peculiarity arises from the teeth having taken a still more horizontal inclination; they are now crowded together; and, from the irregularity of their wear, may assume the pointed figure indicated in the plate. The change of colour also has become more decided, and the general indications, which have been before alluded to, are more marked. After what has been so frequently repeated concerning the deceptive character of the tables in extreme age, little, perhaps, need be added to that subject. Nevertheless, to convey an idea of the appearances which these surfaces may assume, subjoined are wood-cuts taken from authenticated mouths, for the inspection of which I am indebted to the liberality of Mr. Ernes, of Dockhead, who has paid great attention to the changes of the teeth. To the honour of that gentleman, I may, while confessing the heavy obligations under which his generosity has placed me, here mention, that no member of the veterinary profession had, to my knowledge, under his care so great a number of animals working at a period of life when the horse is usually supposed to be worthless. The majority of these were in good condition, active, and capable of doing every kind of ordinary service. They presented a pleasing spectacle, more than creditable to the talent of him under whose charge they had retained health and vigour. The aspects which the tables of the teeth exhibited, however, were such as set judgment at defiance, and for the purpose of enabling the reader to form his own opinion on the matter, engravings of a few of them are here introduced.
The above wood-cut exhibits the tables and arrangement of the incisors as they were seen in the mouth of an animal which was proved to be no less than twenty-eight years old. Any one, who should base his opinion solely on the marks, must have pronounced the creature to have been no more than five, since none of the infundibula are lost. The semi-circular arrangement also had suffered no very material change, and altogether the contrast with the next representation of the same parts, as they appeared in the mouth of a horse which was but one year older, is very striking.
In the above engraving the teeth are seen to be ranged almost in a line, which is the form they have a disposition to take at this great age. The appearance, here delineated, is more true than the foregoing in its general character, the infundibula being entirely worn out; for the specks in the centre of the tables show, not the remains of the last portion of the marks, but the exposure of the upper extremity of what once was the cavity of the pulp. In the next wood-cut, however, which depicts the tables of the teeth which were in the jaw of a horse, that had reached its thirtieth year, and from which the drawing for the coloured engraving was made, displays a portion of the infundibulum still retained in the corner incisor. The true character of age nevertheless is conspicuous in the form of the tables.
THIRTY YEARS OLD.
The jaw contracted. The lower teeth not
seen when the upper are in view.
SIXTEEN YEARS OLD.
Viewed from the side, only two Incisors
can be seen in the lower jaw.
