[Illustration: AMERICAN DEER.]
The distinctive characteristic of the animals of this group consists in
the texture, shape and manner of growth of their frontal protuberances.
These projections, which are called antlers, and not horns, are bony,
solid, and more or less branching. They do not have the horny casing
which exists in all Hollow-horned Ruminants. They fall off and are
renewed at a certain period every year up to a certain age, and it is
because of this peculiarity that these animals are known as Ruminants
with deciduous horns.
In the full grown animal the antler is composed of a cylindrical or
flattened stem, according to the genus, which is called the brow-antler,
from which branch out at intervals slighter or shorter additions, called
tines or branches. The base of the brow-antler is surrounded by a circle
of small bony excrescences, which afford a passage to the blood vessels
intended to provide for the growth of the antler; these are called
burrs.
There are various terms used to indicate the growth of the antlers. In
the first place, on the brow of the young animal, two small elevations
or knobs are seen to make their appearance, above each of which there
soon grows a projection of cartilage, which finally assumes a bony
texture.
Until they become perfectly hard, these two early sprouts are protected
from any external friction by a kind of velvety skin, which dries up as
soon as the cartilage turns to bone.
The short horns which then adorn its brow take the name of dags. At the
commencement of the third year the dags fall off, but soon after they
are replaced by other and longer ones, which throw out their first
tines; and from this time they are considered as entitled to the name of
antler.
The falling off and periodical renewal of these bony projections is
really a very curious phenomenon. It seems as if it ought to take
several years for the horns to regain, as they do, equal or even larger
dimensions than their predecessors; nevertheless, they shoot out all
complete in the space of a few weeks. Still, the explanation of this
fact is simple enough.
The skin which covers the base of the antlers of this animal is
traversed by a large number of blood vessels, which supply the phosphate
of lime necessary to solidify the bony parts. Up to the time when the
antler has acquired the full growth which it is to attain in each year,
this skin continues to receive the requisite flow of blood; it retains,
in fact, its living action. But as soon as the growth is complete, and
it becomes bony, the burrs increase in size, strangulate the vessels,
and stop the flow of the alimentary fluid. This skin then withers and
comes away from the antler, which, thus laid bare and no longer
receiving nourishment, gradually wastes away or decays, and falls off at
the end of a few months, again making its appearance in the approaching
season.
Nearly all the members of this family are remarkable for the elegance of
their shape, the dignity of their attitudes, the grace and vivacity of
their movements, the slenderness of their limbs, and the sustained
rapidity of their flight. They have a very short tail; moderately sized
and pointed ears, and their eyes are clear and full of gentleness.
The coat of Ruminants which shed their horns is generally brown or
fawn-colored. It is composed of short, close and brittle hair, which
assumes a somewhat woolly nature in the inclement regions of the extreme
north, more especially in the winter season.
These Ruminants live in small droves or herds in forests, on mountains
or plains, and feed on leaves, buds, grass, moss, or the bark of trees,
etc. They are distributed over all the surface of the globe, both in the
hottest and coldest climates. The Reindeer and Elk are peculiar to the
northern regions of both continents; but numerous species are, on the
contrary, found in hot and temperate countries.
The family of Ruminants which shed their horns comprehends three
genera—the Reindeer, the Elk, and the Deer proper—all differing in the
shape and size of their antlers.