The dentition in the Elephants presents several points of considerable interest. In the Indian species, the males alone have well-developed incisors; while both sexes of the African species are provided with them. These—more commonly known as tusks—grow to an enormous size, sometimes reaching the weight of from a hundred and fifty to two hundred pounds. There are no lower incisors, and only two of the molar teeth are to be seen at each side of the jaw at one time. There are six of these in each side, or four-and-twenty in all, in the lifetime of the Elephant, and these present a gradual increase in size as they successively appear. These teeth move forward into their working place in the jaw in regular succession, from behind forwards, each being pushed out by its successor as it gradually becomes worn away. The teeth are worn away, not merely by the food on which the animal lives, but also by the particles of sand and grit entangled in the roots of the herbs torn up for food, and their wear is compensated by the growth and development of the succeeding teeth. In a state of captivity, however, where the food is much more free from extraneous substances than in a state of nature, the teeth are not worn away fast enough to make room for the development of the successors, and it therefore frequently happens that the tooth is deformed by a piling over of the plates of which it is composed.
SIDE VIEW OF MOLAR TOOTH OF INDIAN ELEPHANT.
A, Upper; B, Lower.
The molar or grinding-teeth of the Elephant are for the most part buried in the socket, and present little more than a surface for mastication above the gum. Each is composed of a number of transverse perpendicular plates, built up of a body of dentine, covered by a layer of enamel, and this again by a layer of cement, which fills the interspaces of the plates, and binds together the divisions into one solid mass. Each of these enamel plates, however, in the perfect tooth is united at the base. When these plates of enamel—which stand out in the transverse plates on account of their superior hardness, and cause the grinding surface to be uneven—are worn out, the animal either dies of indigestion, or more often becomes weak, and falls a prey to wild beasts.
LAST LOWER TOOTH OF
AFRICAN ELEPHANT.
LAST LOWER TOOTH OF
INDIAN ELEPHANT.
The difference between the grinders of the Indian and African Elephants is well defined. In the former, the transverse ridges of enamel are narrower, more undulating, and more numerous than in the African, in which latter species the ridges are less parallel, and enclose lozenge-shaped spaces. The cervical vertebræ form a short and stiff series, allowing but a limited motion of the head from side to side, a more extended action being rendered unnecessary by the flexibility of the trunk. With regard to the dorsal vertebræ, they appear to vary in number in both species. In the African species the number varies from twenty to twenty-one, and in the Indian species from nineteen to twenty. As might be expected, the limbs of the Elephant are massive and powerful. In ancient times it was a popular delusion that the legs of an Elephant possessed no joints; and even now people are to be found who believe that the Elephant’s joints move in a contrary direction to that of other quadrupeds. Shakspere evidently enjoyed the popular belief. In Troilus and Cressida, Ulysses, speaking of the stiff demeanour of Ajax towards Achilles, says:—