These are massive animals, walking
upon the extremities of the five toes, with which each foot is
provided, and upon a great tegumentary cushion which unites
these, and forms a flat sole behind them.
The nose is prolonged into a flexible proboscis, which is at
once a strong, and a delicate, organ of prehension. The hairy
covering is scanty in the recent species; but there were abundant
long hair, and an undercoat of wool, in at least one
extinct Proboscidean, the Mammoth (Elephas primigenius
which ranged over Northern Europe and Asia during the glacial
epoch. The pinna of the ear is large and flat. The testes
of the male remain in the abdomen, and the mammae of the
female are placed between the fore-limbs.
The dorso-lumbar vertebrae amount to as many as twentythree,
and not more than three of these are lumbar, so that the
dorsal region is, proportionally, exceedingly long. There are
four sacral vertebra, followed by a comparatively short tail. The
centra of the vertebrae are far more flattened, from before
backward, than those of any other terrestrial mammal, and
this is particularly the case in the cervical region, whence it
follows that the neck is extremely short.
The skull is enormous, even in proportion to the body, its
size arising, in great measure, from the development of air cavities
in the diploe. The interspace between the inner and the
outer tables of the skull is often, in an old elephant, considerably
greater than the diameter of the cerebral cavity itself.
The cranial cavity is elongated and subcylindrical. The supraoccipital
rises far upon the roof of the skull, so that the parietals
are much narrower at the sagittal suture than elsewhere.
The premaxillae are very large, and the nasal bones short, the
nasal passages being nearly vertical. The jugal bone forms
only the middle part of the jugal arcade. The rami of the
mandible have a high perpendicular portion, and they are
largely anchylosed at the symphysis, which is produced into a
sort of spout.
The acromion of the scapula has a recurved process, such
as is frequently found in the Rodents, to which order the Proboscidea
present many curious approximations. There are
no clavicles. In the antebrachium, the radius is permanently
fixed (though not anchylosed) in the prone position, crossing
the ulna obliquely. The carpal and metacarpal bones, and
the phalanges, are remarkable for their short and thick form,
and the manus is larger than the pes.
|Fig. 108. - The skeleton of the African Elephant (Loxadon Africanus).
The ilia are immensely expanded transversely. The femur,
which is not connected by any round ligament to the acetabulum,
is relatively long and slender; and, when the animal is
at rest, is directed perpendicularly to the axis of the trunk,
not bent up, so as to form an acute angle with that axis, as it
is in ordinary quadrupeds. The ham consequently occupies
the middle of the length of the hind-leg; the flexion of which,
at this point, when the animal walks, gives an elephant a gait
which is strikingly different from that of other quadrupeds.
The tibia is relatively short. The fibula is distinct and complete,
and the bones of the pes have the same broad and short
form as those of the manus. The hallux has only a single
phalanx in some species.
have only two kinds of teeth, incisors and
molars, canines being entirely absent. The incisors are composed
of dentine and cement, with or without a longitudinal
belt of enamel, and, in the recent Elephants, are developed
only in the upper jaw. As their growth continues for a long
period, or throughout life, they usually take the form of long
tusks, which project on each side of the upper jaw. The
molar teeth are composed of dentine, enamel, and cement, and
their crowns, when unworn, are always ridged, the ridges very
often being made up of distinct tubercles. The intervals between
the ridges are sometimes, as in the Asiatic Elephant,
exceedingly deep, narrow, and completely filled up with
cement; or, as in the African Elephant, they may be shallow
and open, the cement forming only a thin coat. In the recent
Elephants, only the two incisors are preceded by milk-teeth.
The molars are, altogether, six on each side, above and below;
they come into place and use successively, the hinder ones
moving forward, in proportion as the anterior ones are worn
down by the attrition of those which are opposed to them.
The stomach is simple and elongated, and there is a very
wide caecum. The trilobed liver has no gall-bladder. The
heart has two anterior cavae.
The cerebellum is left uncovered by the cerebral hemispheres;
which, in the existing Elephants, are large, and have greatly-convoluted surfaces.
The male reproductive organs exhibit two very large vesiculae
seminales, and four prostates. The uterus of the female
has two cornua.
Some, if not all, species of the extinct genus Mastodon
were provided with a pair of short tusks in the mandible, in
addition to the large ones in the premaxillae. And in some of
these animals, as in certain other extinct Elephants, the anterior
grinding teeth had vertical successors. The Miocene
, possessed two large, downwardly-directed
tusks, one on each side of the symphysis of the mandible,
while there were none in the upper jaw. The second and the
third anterior grinding teeth had vertical successors.
are, at present, restricted to Asia and
Africa, where they are represented by two very distinct forms to
which the names of Loxodon
) and Euelephas
) proposed by the late Dr. Falconer may be very
properly applied. The oldest rocks in which their remains
occur are of Miocene age. Fossil remains of elephants occur
not only in the Old World, but also in both North and South