116 Animal Life 
Among all living hoofed 
animals perhaps the most re- 
markable and most specialised 
type of dentition is presented 
by the elephants. Nevertheless, 
recent discoveries have enabled 
us to trace this highly-modified 
condition into close connection 
with the ordinary type, although 
it is impossible to allude further 
to this subject on the present 
occasion. As we all know, a 
modern elephant has a single 
pair of tusks (which grow con- 
tinuously throughout life) in the 
upper jaw, and no other front 
teeth whatever. Instead, how- : 
ever, of corresponding to the Fig. 15. Side view of the Dentition of the Indian Hlephant. 
tusks, or canines, of a wild 
boar or a lion, the elephant’s tusks represent one of the three pairs of incisors of the 
latter animals, this being rendered certain by their being implanted in a particular bone 
of the skull. An elephant never has more than portions of two pairs of molar teeth in 
each jaw in use at any one time, and in old age has but one pair, thus having only six 
teeth altogether at this period of its existence. During the whole hfe of an elephant 
there are, however, six pairs of molars developed in both the upper and the lower jaws, 
the first of them beimg quite small and in use only during the period of suckling, while 
the last are the huge grinders, weighing many pounds, with which we are all familiar as 
curiosities. As the smaller and earlier teeth are gradually worn away they are pushed 
out by the teeth immediately behind them, which rise from the Jaw im an are of a 
circle. When the last molar is worn out, the life of the elephant necessarily comes to 
an end; but the great size, mode of succession, and complex structure of the later 
molars renders this process of wearing out very slow indeed, so that the life of an 
elephant may embrace a couple of centuries, or even more. 
No more wonderful grinding-apparatus than that formed by the dentition of the 
Indian elephant (im which species the molars are more complicated than is the case 
in its African relative) is, indeed, to be met with throughout the class of mammals. 
To describe in detail the structure of an elephant’s molar would require more space 
and more figures than the publishers would care to afford. It must accordingly suffice 
to state that the crowns of these teeth are formed by a number of closely-packed 
transverse and vertical plates, made of substances of different hardnesses, and thus 
producing by their wear an uneven surface of great grinding power. In the Indian 
elephant these plates are thinner and more numerous than in the African species, and 
thus form a finer and more efficient mill. The reason of this is not far to seek, 
the Indian species feeding on grass, rice, and foliage, while its African cousin prefers 
roots and tubers, which require much less fine mastication. 
The immediate ancestors of the modern elephants, the extinct mastodons, were 
evidently much shorter-lived animals, as we infer from the nature of their molar teeth 
(Fig. 16). In place of only two, there may be portions of three pairs of molars in 
each jaw in use at the same time, while the teeth themselves are smaller and of less 
complicated structure. The numerous and tall plates of the elephant’s molar are, for 
instance, replaced by from three to five or six low ridges separated by wide valleys, 
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