The little Musk-deer has no sort of horn; but his upper canine teeth are large and form tusks.
The true Deer have antlers (in the male), which they shed every year. The males, and sometimes the females, have canine teeth in the upper jaw. The antlers are dermal bones, that is, are formed in the skin, and do not grow from the skull. They have two rudimentary digits above the hoofs.
The whole of this group, which we may call the Camel and Deer family, are almost wholly defenceless, the Giraffe the most so of all, and, excepting those which are useful in domestication, are threatened with extinction. The Camels and the Llamas, although separated as distantly as Peru and Arabia, have in common the very peculiar habit of snorting most offensively at those who oppress or annoy them.
This large family of Camels and Deer stands between a small one which comprises Pigs, and a very large one, to which Cattle, Sheep, Goats and Antelopes are assigned. Pigs are not ruminants, and have incisor teeth in the upper jaws. Cattle, sheep, &c., like camels and deer, ruminate, and have no cutting teeth in the upper jaw. Their distinctive features are hollow horns (which are present in both sexes), and the invariable absence of tusks.
The canine teeth in all members of the Giraffe group are peculiar, in that they show a cleft in the free edge which divides them into two lobes. These teeth look as if they belonged to the incisors, but various facts prove them to be really the canines. Those of the extinct Sivatherium, and those of the recently discovered Okapi, have similar peculiarities, and thus prove their relationship.
It is curious that our natural history authorities are not yet agreed as to whether the Giraffe has his fore limbs longer than the hind ones or not. Claus and Sedgwick say, “hind legs much shorter, and therefore the back slopes backwards.” Those who have measured the bones, however, say that there is no difference, and that the slope depends entirely upon the setting of the shoulder blade.