In this group of Edentata
zygoma sends down no process from its lateral region, although,
in some rare cases, the anterior part of the arch has a
descending prolongation. The acromion and the coracoid do
not become united. The scaphoid and the trapezium remain
distinct; and the sole of the hind-foot rests upon the ground
by a greater or lesser extent of its whole surface, and not
merely by its outer edge.
The insectivorous Edentates are divisible into
the Mutica, b.
The group of the Mutica
contains the genera Myrmecophaga
, the Ant-eaters of South America.
The bodies of these animals are covered with hair, and they
are provided with very long tails, which are sometimes prehensile.
The skull is greatly elongated, and the small premaxillae
are but loosely connected with it. The jugal arch
is incomplete. In Myrmecophaga
, the pterygoids, which are
very long, stretch back to behind the level of the tympanic
bullae, with the whole inner edges of which they are united
either by bone or by membrane; and as, at the same time, they
unite in the middle line, the roof of the palate is greatly prolonged,
and the posterior nares are bounded below and at the
sides by the pterygoid bones. This arrangement is to be
found in no other Mammals, except some Cetacea
, nor in any
, except the Crocodiles. The mandible is
very slender, the ascending ramus, coroncid process, and angle
of the jaw, being obsolete. The articular surface of the condyle
is flat. The hyoid is placed far back beneath the posterioi
cervical vertebrae, and is connected with the skull only by
muscles. The thyroid and the cricoid cartilages are ossified.
The dorso-lumbar vertebrae are complicated by the presence
of accessory articular processes. Well-developed clavicles are
present in the climbing Cyclothurus didactylus,
but they are
incomplete, or absent, in the other species. In the manus, the
outer digit, or digits, are devoid of claws, and the weight of
the body, when the animal walks, is supported upon its outer
edge, which is frequently thick and callous. The pes has five
digits, each provided with a strong nail, and the sole rests
upon the ground.
The tongue is extraordinarily long and protractile; it is
not connected to the hyoid by the ordinary hyo-glossus
but long muscles, which are attached to the sternum
), retract it, while it is protracted by the genioglossi
Immense submaxillary glands extend back over the thorax,
and cover the tongue with a viscid secretion, when it is thrust into
the nests of the ants, upon which the Myrmecophaga
preys. The insects, entangled by thousands in this substitute
for birdlime, are then dragged back into the mouth of the
Ant-eater, and swallowed. The pyloric portion of the stomach
is so exceedingly thick and muscular as to be comparable to
a gizzard. The brain presents numerous convolutions, and
has a large corpus callosura. The anterior commissure is also
remarkably large. In the female, the uterus is simple, but has
a double os uteri.
The placenta is said to be discoidal in
form in Myrmecophaga didactyla.
The group of the Squamata
contains the single genus Manis,
species of which are found both in Africa and Southern
Asia. In these singular animals, the body is covered with
overlapping, horny scales, and they have the power of rolling
up like hedgehogs. In walking, the long claws of the forefoot
are bent under, so that their dorsal surfaces rest upon the
ground, while the weight of the hinder part of the body is
thrown upon the flat soles of the hind-feet.
The skull is elongated, the premaxilla is small, and the
zygoma usually incomplete. The pterygoids are much elongated
and extend backward beyond the bullate tympanic
bones, but they do not unite in the middle line. The mandible
has no ascending ramus, and its condyle is flat. Air-passages
in the walls of the skull place one tympanum in communication
with the other and extind into the squamosal bone. There
are no clavicles. The "xiphoid" extremity of the sternum is
large, and may be produced into two long cornua, as in Lizards.
The mouth is toothless.
The large salivary glands extend on to the thorax. The
stomach is divided into a thin-walled cardiac sac, lined by a
dense epithelium, and a thick muscular pyloric portion. It
is always found to contain numerous stones. The placenta
appears to be diffuse and non-deciduate.
are also represented only by a single
, which is a native of South Africa. The
body is hairy, provided with thoracic and inguinal teats, and
the ears are long, not short or rudimentary, as in the preceding
genera. In both the fore-and the hind-limbs, the foot rests
evenly upon the ground and mainly upon the plantar surfaces
of the strong claws. The fore-foot has only four digits, in
consequence of the absence of the pollex, while the hind-foot
The skull has a complete zygoma and well-developed premaxillae.
The lachrymal bone is large, and the lachrymal
foramen is situated upon the face. The tympanic bone is
annular, and the periotic mass so large, and enters so much
into the lateral walls of the skull, as to remind one of its proportions
in the Sauropsida
. The mandible has an ascending
ramus. The clavicules are complete.
The jaws are provided with teeth, the substance of which
is traversed by a great number of parallel vertical canals.
These teeth are rootless molars, and the greatest number
which has been observed is 8.8/6.6, but the small anterior ones
fall out, reducing them to 5.6/4.4. The hindermost, and the small
anterior ones, are simple cylinders, but the middle teeth present
a longitudinal groove on each side.
The submaxillary glands are very large. The stomach is
divided into a right and a left portion; the former having very
thick and muscular walls. The intestine has a cascum. It is
stated that the ductus arteriosus
long remains open.
The two uteri open separately into the vagina. The placenta
is deciduate and discoidal.
In the Loricata
, the dorsal region of the body is covered
by a carapace, composed of epidermal scales, and of suturally
united quadrate, or polygonal, scutes, which are dermal ossifications,
so that the whole structure is strictly comparable to
the dorsal shield of a crocodile. These are the only Mammals
in which such scutes exist. When fully developed, the dorsal
armor of one of these animals presents five distinct shields,
the edges of which permit of a certain amount of motion between
them. One of these covers the head, and is called cephalic;
protects the back of the neck; a
covers the shoulders like a great cape; a fourth,
usually consisting of a number of tree and movable segments,
covers the posterior dorsal and lumbar region, as the thoracoabdominal
shield; and the fifth, the pelvic
, is attached by its
deeper surface to the ilia and ischia, and arches over the rump
like a half dome. The tail may further be invested by a series
of incomplete bony rings and scattered scales; and scutes are
distributed over the limbs. In one genus, Chlamydophorus
the scutes are developed only in the pelvic region.
In the skull the premaxillae are well developed, and the
zygoma is complete. The mandibular ramus usually has a
well-developed ascending portion and coronoid process.
Clavicles are present. The fore-and the hind-feet rest upon
the ground evenly, and indeed the hind-limbs are usually
plantigrade, or nearly so; but, in the singular genus Tolypeutes
the fore-foot is supported upon the extremities of the
long nails. The pollex is always present in the fore-foot, but
the fifth digit sometimes becomes rudimentary. There are
always five toes in the hind-foot.
In the genus Euphractes
, each premaxilla contains a single
tooth, which, consequently, is an incisor.
This group contains two divisions, the Dasypodidae
; both are South American, but the former
is chiefly composed of living animals, while the latter only
contains an extinct genus.
are what are commonly known by the
name of Armadillos
. In this division the thoraco-abdominal
shield, when present, as it is in all the genera except Chlamydophorus
consists of, at fewest, three, and, at most, thirteen,
transverse movable zones of scutes.
In the skull, the ends of the nasal bones project beyond
the level of the premaxillae, so that the nasal aperture looks
more or less downward. The premaxillae have a considerable
size, and articulate largely with the nasals. The anterior part
of the jugal arch offers, at most, a rudimentary downward prolongation.
The mandibular symphysis has but a moderate
length, and the posterior alveoli of the mandibles do not extend
along the inner face of the ascending portion of the
ramus of the jaw.
The teeth of the upper and lower jaws alternate, and
hence their grinding surfaces wear down into ridges.
The odontoid vertebra is anchylosed with a greater or
smaller number of its successors. The cervical vertebrae
which follow these have peculiar accessory articular surfaces;
and the hinder dorsal and the lumbar vertebrae are also provided
with accessory articular facets and processes. A number
of the anterior caudal vertebrae are always anchylosed with one
another, and with the true sacrals, to form the long sacrum;
and the transverse processes of some of these caudal vertebrae
abut against the inner surfaces of the ischia, and become anchylosed
The first rib is broad and flattened, and the anterior piece
of the sternum is expanded. The succeeding vertebral ribs
arc connected by ossified sternal ribs with the sternum, and
these are articulated, not only with the sternum, but with one
In the carpus, the cuneiform bone bends round the uniform,
and articulates with the fifth metacarpal, when that
bone is present. The ungual phalanges of the manus are
long and pointed. The femur has a third trochanter, and
the four inner metatarsals are much longer than they are
The division of the Glyptodontidae
contains the single
, which is essentially a large armadillo; but
it departs, in some respects, not only from all these animals,
but from all other Mammalia
, and even stands alone among
The carapace covers the whole body, but presents no
movable thoraco-abdominal zones, inasmuch as it consists of
polygonal plates firmly united together, and fringed by a margin
of scutes with raised conical surfaces.
The nasal bones are short and broad, and their free ends
do not project so far as the premaxillae; whence the anterior
nasal aperture looks slightly upward as well as forward. The
premaxillae, however, are very small bones, and, if they unite
with the nasals at all, do so for a very short distance. The anterior
portion of the jugal arch gives off a great downward process.
The mandibular symphysis is very long, and the posterior
alveoli of the mandible are situated upon the inner face of the
very high perpendicular part of the ramus. The teeth are
trilobed, two deep grooves excavating their inner and their
outer surfaces. And, as the crowns of those of each jaw arc
placed opposite each other, they are worn flat.
The last cervical and the anterior dorsal vertebrae are
anchylosed together into a single "tri-vertebral" bone which
moves by a hinge-joint upon the third dorsal. This and the
succeeding dorso-lumbar vertebrae are immovably united, and,
for the most part, anchylosed, together. The head of the first
rib is engaged in the socket furnished to it by the tri-vertebral
bone in such a manner as to be immovable, and the rib is not
flat, but rounded and columnar.
In the carpus, the cuneiform bone articulates with the
fourth, as well as with the fifth metacarpal, the latter bone
being entirely supported by the cuneiform. The metacarpals
and phalanges are all very short and broad. The pollex is
rudimentary, while the fifth digit is fully developed.
The supra-condyloid ridge of the femur is not distinct from
the third trochanter, even if the latter can be said to exist at
all. The metatarsal bones are as broad as they are long, or
broader; and, as in the fore-foot, the majority of the phalangea
are comparatively short and truncated.