In the commonly-recognized members
of this division of the Artiodactyla
there is never more
than one pair of incisors, and that the outermost, in the upper
jaw of the adult. Canines may or may not exist in the upper
jaw; they are always present in the lower jaw, and are generally
inclined forward and closely approximated to the incisors,
which they usually resemble in form. It consequently
happens that they are often reckoned as incisors, and Rumiaants
are said to possess eight cutting teeth in the lower jaw.
With one exception (Hyoemoschus)
, the metacarpal and
metatarsal bones of the third and fourth digits early become
anchylosed together into a single, so-called cannon-bone.
There is a peculiar bone called malleolar,
which takes the
place of the distal end of the fibula, articulating below with
the calcaneum and above with the astragalus.
The great majority of the Ruminantia possess horns, the
bony supports, or cores, of which are developed on each side
of the middle line; and, except in the Giraffe, are outgrowths
of the frontal bones.
The stomach has, at fewest, three divisions; and, in the
majority of the Ruminantia, it has four compartments.
If the stomach of a typical Ruminant, such as a Sheep or
an Ox, be examined, it will be found to be divisible into two
principal moieties, the one cardiac and the other pyloric, while
each of these is again subdivided into two others. Thus the
extreme cardiac end of the cardiac moiety is dilated into an
enormous sac of irregular form, the mucous membrane of
which is raised up into a vast number of close-set papillae.
This chamber is the Rumen
, or Paunch
. It communicates,
by a wide aperture, with a much smaller chamber, which constitutes the
second subdivision of the cardiac moiety. This is
called the Reticulum
, or Honeycomb
stomach, from the fact
that its mucous membrane is raised up into a great number of
folds, which cross one another at right angles, and, in this
way, enclose a multitude of hexagonal-sided cells. The reticulum
communicates by a narrow aperture with the first subdivision
of the pyloric moiety, which is somewhat more elongated
in form. The mucous membrane of this subdivision ia
produced into a vast number of longitudinal folds of various
heights, but the majority of them are sufficiently large to extend
almost completely across the cavity of the chamber;
they thus reduce that cavity to a series of narrow radiating
clefts interposed between the lamellae. When this portion of
the stomach is slit open, longitudinally, the lamellae fall apart
like the leaves of a book, whence it has received the fanciful
name of the Psalterium
from anatomists, while butchers give
it that of Manyplies.
|Fig. 102. - A, the stomach of a Sheep. B, that of a Musk-deer (Tragulus). oe., aesophagus; Rn., rumen; Ret., reticulum; Ps., psalterium; A., Ab, abomasum; Du,.
duodenum; Py, pylorus.
The fourth segment of the stomach, or
second subdivision of the pyloric moiety, is termed the Abomasum
stomach. This portion is comparatively
slender and elonguted, and its mucous membrane has a totally
different character from that of the other three segments, being
soft, highly vascular, and glandular, and raised into only a few
It will be observed that the psalterium is so constructed as
to play the part of a very efficient strainer between the reticulum
and the abomasum; nothing but very finely-divided, or
semi-fluid matter, being capable of traversing the interstices
of its lamellae.
The gastric aperture of the oesophagus is situated at the
junction of the paunch and the reticulum; the margins of its
opening are raised into muscular folds, and are produced,
parallel with one another, along the roof of the reticulum to
the opening which leads into the psalterium. When the lips
of this groove are approximated together, a canal is formed,
which conducts directly from the oesophagus to the psalterium.
A Ruminant, when feeding, crops the grass rapidly and
greedily, seizing it with its tongue and biting off the bundle
of blades thus collected, by pressing the lower incisors against
the callous pad formed by the gum which covers the premaxillae.
The bunches of grass are then hastily swallowed,
accompanied by abundant saliva. After grazing until its appetite
is satisfied, the Ruminant lies down, usually inclining
the body to one side, and remains quiescent for a certain space
of time. A sudden movement of the flanks is then observed,
very similar to that which might be produced by a hiccough;
and careful watching of the long neck will show that something
is, at the same time, quickly forced up the gullet into
the cavity of the mouth. This is a bolus of grass, which has
been sodden in the fluids contained in the stomach, and is returned,
saturated with them, to be masticated. In an ordinary
Ruminant this operation of mastication is always performed in
the same way. The lower jaw makes a first stroke, say in the
direction from left to right, while the second stroke, and all
those which follow it until the bolus is sufficiently masticated,
take place from right to left, or in the opposite direction to
that of the first. While the mastication is going on, fresh
quantities of saliva are poured into the mouth, and, when the
grass is thoroughly ground up, the semifluid product is passed
back into the pharynx and swallowed once more. These
actions are repeated until the greater portion of the grass
which has been cropped is pulpified.
The precise nature of the operation, the external features
of which have now been described, has been the subject of
much investigation and discussion. The following points appear
to have been clearly established:
1. Rumination is altogether prevented by paralysis of the
abdominal muscles, and it is a good deal impeded by any interference
with the free action of the diaphragm.
2. Neither the paunch, nor the reticulum, ever becomes
completely emptied by the process of regurgitation. The
paunch is found half full of sodden fodder, even in animals
which have perished by starvation.
3. When solid substances are swallowed, they pass indifferently
into the rumen, or reticulum, and are constantly driven
backward and forward, from the one into the other, by peristaltic
actions of the walls of the stomach.
4. Fluids may pass either into the paunch and the reticulum;
or into the psalterium, and thence at once into the
fourth stomach, according to circumstances.
5. Rumination is perfectly well effected after the lips of
the oesophageal groove have been closely united by wire
It would appear, therefore, that the cropped grass passes
into the reticulum and rumen, and is macerated in them. But
there is no reason to believe that the reticulum takes any
special share in modelling the boluses which have to be returned
into the mouth. More probably, a sudden and simultaneous
contraction of the diaphragm and of the abdominal
muscles compresses the contents of the rumen and reticulum,
and drives the sodden fodder against the cardiac aperture of
the stomach. This opens, and then the cardiac end of the
oesophagus, becoming passively dilated, receives as much of the
fodder as it will contain. The cardiac aperture now becoming
closed, the bolus, thus shut off, is propelled, by the reversed
peristaltic action of the muscular walls of the oesophagus, into
the mouth, where it undergoes the thorough mastication which
has been described.
The sodden fodder is prevented from passing out of the
psalterial aperture of the reticulum, in part by the narrowness
of that aperture, and in part by the fine grating formed by the
edges of the psalterial lamina. But when the semifluid
matter, returned after mastication, once more reaches the
cardia, it is compelled to pass toward the psalterial end of the
reticulum (even apart from the guidance afforded by the lips
of the oesophageal groove) on account of the direction of the
oesophagus and the bounding of the cardiac aperture, on the
side of the rumen, by a raised ridge. The chewed matter thus
flowing over the surface of the more solid contents of the reticulum
reaches the psalterium; and, in consequence of the fine
state of division of its solids, readily traverses the interspaces
of the lamellae of that organ, and passes into the fourth
stomach, there to be submitted to the action of the gastric
juice and to undergo the digestion of the protein compounds,
which have remained unaffected by the previous mastication
are divided into three groups: a.
, and c.
are a remarkable family, formerly united
with the genus Moschus,
and still commonly known under the
name of Musk Deer, though they are devoid of the musk-sac
and, in other respects, are totally different from Moschus.
They are at present restricted to Southern Asia and Africa;
and they are particularly interesting, as affording, in many
respects, a connecting link between the typical Ruminants and
the other Artiodactyla,
especially the Anoplotheridae.
the second and fifth digits are complete in both fore-and hindfeet,
and the metacarpals and metatarsals of the third and
fourth digits unite very late, or, as in one genus, Hyoemoschus,
not at all. The canines are well developed in both jaws, and
the premolar teeth are sharp and cutting.
The oesophagus opens at the junction of the rumen with
the reticulum, the communication between the two being very
wide (Fig. 102 B). The epithelium of the rumen is papillate,
and there are two oesophageal folds, as in ordinary Ruminants,
but the psalterium is represented only by a very short and
narrow tube, the lining membrane of which is devoid of folds.
The surface of the hemispheres of the brain has fewer
convolutions than in any other Ruminants, though this may
very possibly be connected with the small size of the animal;
as it is a general rule that, within the same group, the brain is
less convoluted in small than in large animals.
The blood-corpuscles, small in all Ruminantia,
minute in the Tragulidae
, not exceeding 1/10000 of an inch
in diameter. They have circular contours.
The placenta is very nearly diffuse
, the foetal villi being
scattered over the chorion in bands, not collected into cotyledons.
As further remarkable peculiarities of this group may be
mentioned the anchylosis of the malleolar bone with the tibia,
and the tendency to ossification in the pelvic ligaments and
of the aponeurosis of the, muscles of the back, in adult males.
Finally, the navicular, cuboid, and ectocuneiform bones in the
tarsus are all anchylosed together. If, as is probable, Xiphodon
is one of the Tragulidae
, the group has existed since the
are, like the preceding group, unguligrade,
but the outer metacarpals and metatarsals are incomplete
at their proximal ends, and the middle ones are early
anchylosed into a cannon-bone. The malleolar bone is always
distinct. The navicular and the cuboid bones of the tarsus are
anchylosed together, but rarely with any other tarsal bone.
The premaxilla is devoid of teeth in the adult. The stomach
has the structure which has been described as typical.
The blood-corpuscles are circular, and may have a diameter
of as little as 1/5000 of an inch.
The foetal villi are gathered together into bunches or cotyledons,
which may present either a convex or a concave face
toward the uterus. They are received into persistent elevations
of the mucous membrane of the uterus, the surfaces of
which present a reverse curvature.
All the Cotylophora
, the true Musk Deer,
are provided with horns, but these horns are of two kinds.
The bony core, in the one case, is ensheathed in a strong horny
epidermic case; while, in the other, the epidermis of the integument
which covers the core does not become so modified.
In the former kind of horn, the core becomes excavated by the
extension into it of the frontal sinuses, whence the Ruminants
which possess such horns are not unfrequently called Cavicornia
(Antelopes, Sheep, Goats, Oxen). As a general rule,
the horny sheath persists throughout life, growing with the
growth of the core. But in the remarkable Prong-horned
Antelope of North America (Antilocapra)
, the horny sheath
is annually shed and replaced by a newly-formed one.
Of the second kind of horn, or that which acquires no homy
sheath, there are also two kinds. In the Giraffe, the horncores
are attached over the coronal suture, at the junction of the frontal and
parietal bones, with which they are not anchylosed; they persist
throughout life, and are always covered
by a soft and hairy integument.
In the Deer, on the other hand, the frontal bones grow out
into solid processes, which are, at first, covered by soft and
hairy integument; generally they are developed in the male
sex only, but both sexes have them in the Reindeer. The
horns attain their full size very rapidly, and tben a circular
ridge, which makes its appearance at a short distance from the
root of the horn and is called the "burr,"
divides the horn into
on the skull-side of the burr, and the "beam"
on the opposite side. The circulation in the vessels of the beam
now gradually languishes, its integument dies and peels off, and
the dead bony substance beneath is exposed. Absorption and
sloughing next occur at the extremity of the pedicel
, just as
might happen in any other case of necrosis. The beam and
burr are shed, and the end of the pedicel scabbing over, fresh
integument gradually grows up under the scab, and eventually
restores to the extremity of the pedicel its pristine smooth and
The rapidity with which the development of bony matter
into Deer-horn takes place is wonderful, horns weighing
seventy-two lbs. having been produced in ten weeks.
are represented in all parts of the world
except the Australian and Novo-Zelanian provinces. They
have not yet been traced back farther than the miocene epoch.
) are devoid of horns; and,
unlike the other Ruminants, they walk upon the palmar and
plantar surfaces of the phalanges of the third and fourth toes,
which are alone developed. Broad integumentary cushions
form a sole to the foot; while the nails are flattened and can
hardly be called hoofs.
The arches of the cervical vertebrae, and not their transverse
processes, are perforated by the canal of the vertebral
artery; a character which the camels share with the Macrauchenidae
The metacarpals are separated by a deep cleft, and the
distal phalanges of the digits are nearly symmetrical in themselves.
The distal facets of the astragalus are more unequal
than in the other Ruminantia
, and the navicular and cuboid
bones are not anchylosed together.
The premaxillae have a single strong outer incisor on each
side. Large curved and pointed canines are developed in each
jaw, and are quite distinct from the series of the incisors in
the mandible. There are not more than five grinding teeth in
a continuous series above and below.
The stomach is unlike that of the typical Ruminants. The
oesophagus opens directly into the paunch, which is lined by a
smooth, not papillose, epithelial coat. From its walls, at
least two sets of diverticula, with comparatively narrow
mouths, are developed. These, the so-called "water-cells."
serve to strain off from the contents of the paunch, and to
retain in store, a considerable quantity of water. The reticulum
is sharply defined from the rumen, and communicates with
it by a comparatively small aperture. The oesophageal groove
is bounded by only one ridge, which lies upon its left side.
The psalterium is reduced to a mere tubular passage, without
laminae; and the abomasum is large, and has the ordinary
structure. The pyloric end of the duodenum is considerably
dilated, and has been taken for a division of the stomach. The
caecum is short and simple. By a remarkable exception
among the Mammalia
, the red blood-corpuscles are elliptical.
The foetal villi are scattered evenly over the chorion, so that
the placenta is diffuse.
While the Tragulidae
connect the typical Ruminants with
the non-ruminant Artiodaotyles, the Camelidae
, on the other
hand, link them with Macrauchenia
and the Perissodactyles
are at present represented by two very
distinct groups-the Camels of the Old World and the Llamas
of the New. They occur in the fossil state as far back as the