of the dorsal and lumbar vertebra?. The
number of sacral vertebrae is seven, and the
transverse processes are separated from
each other, the three upper of which are long
and strong, and are articulated by their tips to
the ilia. The facet on the extremity of the
first looks upward and outward, and that on
the second, on the contrary, downward and
outward, and form projections which impinge
upon the iliac facet. This arrangement in the
Wombat like that in the Tapir, is closely ana-
logous to the formation of the sacral "joggles,"
and the alteration of the inclination of the
sacral wedge in Man, at the point of the auri-
cular surface opposite the second sacral piece,
substituting for upward, backwards, and for
downward, forwards, a change consequent on
the difference between the prone and erect
positions. Caudal pieces are numerous.
The ilia are comparatively short and ex-
panded considerably, and are curved out-
wards in a remarkably strong, broad, hook-
like process at the anterior superior spine.
They are placed very obliquely on the spine,
being at an angle of 160 with the lumbar
portion of the great dorsal curvature. The
ischia are thick, long, and massy, and in a
right line with the ilia. They have cu-
riously bifurcated tuberosities, one tubercular
projection turning inward, and the other
longer, curving outward, in another remark-
able and strong hook-like process, to which
formation we have before remarked a tendency
in the Hare and other Rodents (Jig. 98. e).
These processes, like those on the ilia, afford
a powerful hold and leverage to the strong
muscles of the hinder extremities, much used
by the animal in its burrowing habits. These
hook-like processes of the ischia are formed
by a Y-shaped apophysis analogous to that of
tne tuberosity in man. The pubes are short
and thick ; and the symphysis is parallel to
the spine, very long, and joined in very ex-
tensively by the vertically directed rami of the
ischia.
The marsupial bones of the Wombat are long,
flat, rounded and expanded at their free extre-
mities, and articulated to the anterior border of
the pubes in the position of the crests by two
articular facets separated by an arched interval.
Ilio-pectineal spines are present, and of large
size.
The whole pelvis of the Wombat is large and
massy, though the openings and outlets are
proportionably very small. It has a flattened
appearance antero-posteriorly, so that the
anterior outlet has its greatest diameter trans-
versely placed.
In the Myrmecobius fasciatus this flattened
appearance of the pelvis is still more remark-
able.
In the Opossums, Pcramcles, and Pha-
langers, there is but one sacral vertebra, which,
in the Phalangista Cookii y is ankylosed to the
last lumbar vertebra.
The pelvis of the Thylacinus Cynocephalus
approaches closely in many respects to the
type of the Carnivora, like many of the
peculiarities of this animal. The sacrum pre-
sents no angle ; the ilia are massy, somewhat
short, and less oblique than those of the
Wombat ; the ischia are also short and thick,
and are placed at an open angle (170) with
the ilia, while the pubes are short and di-
rected almost horizontally inwards, making
an antero-posterior angle with the ilia as little
as 115. The whole appearance of the pelvis
is massy, with small openings. It has neither
the oblique appearance and exaggerated pro-
cesses of the Wombat, nor the elongation and
wide outlets of the Kangaroo, while its well-
marked ilio-pubic angle contrasts much with
both, and shows a strong similarity to the
Carnivora.
In the Kangaroos, the sacrum is in the line
of the lumbar curve, and differs in little but
size and breadth from the preceding vertebrae.
There are twt> sacral vertebra?, articulating
with the ilia, their transverse processes being
long and coalesced, but the spinous processes
distinct. In the Potoroo there is one only,
with large lateral processes. The caudal
vertebrae are numerous and very strong, and
their upper normal spines encroach much on
the diameter of the pelvic cavity and posterior
outlet. The ilia have short, strong, and pris-
matic shafts as in the Rodents, with alae of the
same shape, much elongated and turned out-
wards, though in a much less degree than in the
Wombat, and terminating in narrow clubbed
crests (jig. 99. g). There is a rudimentary
inferior anterior spine (/*). The upper part of
the iliac wing projects much on the dorsal
aspect of the spinal column, forming with it
an angle of 140 (see fig. 112. 9.). The ischia
are very long, broad, and strong, and have
much-expanded tuberosities with an outward
curvature (fig. 99. e). These are united in a
median symphysis by a single V-shaped epi-
physis (c), divided, in the adult, by a suture
from the ischia. The tuberosities support also
another epiphysis on each side posteriorly at e,
the anterior ischial rami being almost deficient.
The ilia and ischia are very nearly in a direct
line. The pubes are moderately long, slender,
and directed much downward, so as to give to
the anterior outlet a triangular shape, with the
base at the broad sacrum, and the apex at the
pubic symphysis. The ilio-pubic angle is 135.
The marsupial bones (a y b ) are smaller,
rounder, and more curved externally than in
the Wombat. Their free extremities are tuber-
culated and not flattened, and they are articu-
lated to the pubic crest near the symphysis by
a single facet only, the inner, the position of
the outer one being marked by a slight tubercle
(6). The ilio-pectineal spines (d) are very
large, for the attachment of powerful psoae
muscles.
The direction of the ischio-pubic symphysis
PELVIS.
161
(/) in the Kangaroo, Phascogale, and Potoroo,
is not parallel with the spinal column, but
Fig. 99.
Pelvis of the Kangaroo, showing the marsupial bones
(a a) and inter-sciatic epiphysls (c).
oblique in the opposite direction to the human
symphysis, so that if prolonged forwards the
line of direction would cut the spinal column
at an obtuse angle. This makes the posterior
opening larger in its antero-posterior diameter
than it otherwise would be, and allows for
the great encroachment of the caudal ver-
tebrae posteriorly. The sciatic notch is long
and narrow, corresponding to the great length
of the ischia ; and the foramen obturatorium is
large and elongated antero-posteriorly from
the same cause. In the Dasyurus and Pe-
taurists, the ischio-pubic symphysis is oblique
in the opposite direction. The antero-pos-
terior diameter of the anterior outlet in the
Kangaroo is greater than the transverse by
about half an inch ; but at the posterior outlet,
the transverse is a little greater, from the pro-
jection of the caudal spines before mentioned.
The pelvic cavity is deep in the Marsupialia,
and its. openings are small in proportion to the
size of the animal, since the foetus is expelled
before it is full grown, and placed on the nipples
in the marsupial pouch to complete its deve-
lopment into a state of independent existence.
But the proportion between the pelvic open-
ings and the size of the foetal head, at the
period of expulsion, is very remote. Even in
the PetauristSy whose pelves are the smallest,
the cavity and openings are six times the size
of the foetal head.
The muscles of the tail and legs attached
to the pelvis are, in the Kangaroos, very
powerful to perform their prodigious leaps,
especially the gracilis and biceps. The glutei,
however, are not large, since the trunk is not
held erect on the legs by these muscles, but is
suspended, as it were, between the femurs, and
supported in front by the largely developed
psoas muscles, and behind by the powerful tail,
used as a propelling organ by the sudden
action of its flexor muscles.
The pelvis of the Monotremata resembles
in general appearance the reptile type, although
Snjyp.
in some other respects these curious animals,
especially the Ornithorhyncus, approach the
Birds. The sacrum of the Ornithorhyncus is
composed of two vertebras, separated, as in
the Saurian reptiles, and placed in the line of
the lumbar curve, differing little in appearance
from the lumbar vertebrae. In the Echidna
are three sacral vertebrae, also separated and
all uniting with the ilia.
The ilia are short, thick, and prismatic, and
project above the spine at an angle of 140 as
high as the sacral spines, and presenting, in the
Ornithorhyncus, considerable eversion of the
alae, and, in a much less degree, in the Echidna
also. The ischia are short, bent upwards in the
former, and project backwards at the tuberosi-
ties in an angular spine, most marked in the
Ornithorhyncus, and giving a reptile-like ap-
pearance. The pubes are broad and short,
placed at a marked angle with the ilia, 1 10 in
the Echidna hystrix and 120 in the Ornitho-
rhyncus, and uniting by broad plate-like rami
with the ischial rami, which form with them
a long ischio-pubic symphysis. The ischio-
pubic plate thus formed is very like that seen
in the reptiles.
The marsupial bones are also present, and
are very large and strong in this class, although
not provided with a pouch. In the Ornitho-
rhyncus they are broad and triangular, articu-
lated by the base to the whole length of the
pubic crest meeting in the median line, and
with their rounded apices directed forwards
and outwards. In the Echidna they are longer,
rounder, more pointed and less everted, with
two articular processes at the pubic extremity
(see fig. 177. Art. Manofremata).
The ilio-pectineal spines are also very large in
the Ornithorhyncus, and in a less degree in the
Echidna. The obturator foramina are small.
The three pelvic bones are united at the
cotyloids by bony union in the Ornithorhyncus.
In the Echidna hystrix, the union of these
bones is, however, effected by cartilage only,
and the acetabula are perforated by a consider-
able opening into the pelvic cavity, constituting
another remarkable reptile-like peculiarity.
Having traced the Mammalian pelvis to a
form presenting somewhat of the reptile type
in the Monotremes, we may now recur back
to an order of animals which, from their
general organisation, are connected closely to
the order of primates, and are usually placed
much higher in the animal scale than the
position here assigned to them.
These are the Sloths or Tardigrades, which
form the connecting link between theSimife and
Edentata proper. Their pelvic peculiarities,
however, ally them more closely to the Birds.
The moststriking of these is the ossification of
the ilia and ischia to the broad sacrum, by
transformation of the sacro-iliac and sacro-
sciatic ligaments. We have already noticed tin
exceptional example of this coalescence in
the Ruminants, in the Meminna or pigmy
Chevrotain. But the pelvis of the Edentata
also presents a diminution of the pubic sym-
physis, and the absence of the ischia from
this junction, a separation which is carried
M
162
PELVIS.
still further in the Insectivora and Cheiroptera.
The increasing obliquity of the pubes also
indicates an approach to the Bird type.
The climbing habits of the Sloths produce a
habitual vertical position of the trunk, re-
quiring for the support of the abdominal
viscera large open pelves.
In the Ai {Bradyptu tridactylus) the pelvis
{fig. 100.) is remarkably slender, expanded,
shallow and horizontal in direction, the pelvic
openings being very large and round, and the
antero-posterior diameters little larger than the
transverse. The ankylosis of the innominate
bones to the sacrum in these animals gives a
great firmness to the support of the otherwise
feeble hinder extremities, and with the great
distance of separation of the acetabula, which
are small and shallow, assists to a considerable
degree their climbing and holding powers, and
to produce that slowness and awkwardness of
motion which has given them the name of
Tardigrades.
Fig. 100.
Pelvis of the Ai, anterior view.
The sacrum is large, both in length and
breadth, very flat, with large, open foramina,
and presenting a flattened surface in place of
the posterior spines and tuberosities. It is
composed of five vertebrae, of which the three
upper (e) as well as the last lumbar (g) are
ankylosed to the ilia (&). The union of the
last lumbar seems to result from an extension
of ossification in the ilio-lumbar ligament
(0, and contributes much to increase the
steadiness of the spinal column on the pelvis.
The coccyx is triangular, little curved, broad
and short, and is composed of six pieces. In
some species it is prolonged into a tail*
The ilia are short and slender, with much-
expanded wings, having an anterior concavity
and a plane surface posteriorly. They are
ossified to the sacrum at an early period.
The ischia are short and slender, and united
to the last sacral vertebra, and more slightly
to the two above it, by ossification of the
great sacro- sciatic ligament (), which gives to
the angle of the bone an expanded appear-
ance, and encloses a round, wide sacro-sciatic
foramen (d), above and behind the cotyloid
cavity. The tuberosities are small, and the
inferior rami (/) are long and slender, enclosing
with the pubis a very large obturator foramen,
having its long diameter from side to side, and
do not join in symphysis. The pubes (//) are
long and slender, their rami united in a V shape,
with the angles meeting to form a very short
symphysis (c), which is sometimes ossified, and
presenting a very slight ilio-pectineal spine (i).
The lumbo-Hiac angle in the adult Bradypus is
about 145, and the ilio-pubic about 155,
being only about 25 from a right line as in
the human pelvis. The ilio-ischial angle also
approaches the human standard in being di-
minished to 135.
This diminution of the ilio-ischial angle
is still more remarkably shown in the My-
lodon and Megatherium fossil gigantic Sloths,
which approach more closely to Man in this
respect than any other Mammalian.
The osseous system of the fossil Mytodon
robustus closely resembles that of the Sloths,
differing from thenr, however, by presenting a
continued sacral crest, and more expanded ilia
{fig. 101.). According to Professor Owen, in
his valuable monograph on the specimen in the
Hunterian Museum, the sacrum really con-
sists of seven vertebras, but by ankylosis with
the three lumbar and last dorsal includes
eleven vertebrae, and forms one strong and con-
tinuous bony mass along the whole lumbar re-
gion (a). Its total length is 2 feet 4 inches,
and it gradually increases in breadth to the
sacro-iliac union (<?), which is formed by the
first, second, and third true sacral vertebras, and
there presents its greatest breadth. It then
contracts slightly, and, at the sixth and last, ex-
pands again to join the ischia (d). It is firmly
united by ankylosis both to the ilia and ischia.
Its anterior surface is curved both laterally
and vertically. The spinal canal is very wide,
and the foramina passing from it mark the
primary vertebral divisions. The whole of
the eleven spinous processes of the ankylosed
vertebras form a remarkable curved crest pos-
teriorly (g). There are twenty-one caudal ver-
tebras, which doubtless, in the living animal,
contributed to support the body by applica-
tion to the limbs of the trees upon which it
climbed, and were strongly supported by the
sacro-sciatic ossification.
The innominate bones are very large. The
iliac wings are much spread out, widety con-
cave anteriorly, and slightly convex posteriorly,
these surfaces being directed forwards and
backwards. The iliac crest presents a con-
tinuous, well-arched curve, and at the inner
part of its centre (m) it is prolonged and
curved forward in a lip which overhangs the
anterior fossa, and contributes to support
the bulky viscera. The lips of the crest are
remarkably spread. The posterior superior
spine is continued by an oblique crest of bone
(a) to the lateral tubercles of the lower
sacral vertebras, as if from ossification of the
oblique sacro-iliac ligament. The posterior
inferior spines are continued by a ridge to the
borders of the fifth, sixth, and seventh sacral
pieces into the bony ankylosis of these with
the ischia, which are ankylosed to the same
PELVIS
J63
parts, evidently in the position of the sacro-
sciatic ligaments (d). The ischia (c) are
comparatively short and directed obliquely
backwards and downwards, and have remark-
ably slender tuberosities, as is the"general cha-
racteristic of the Sloths. The inferior rami
(k) slope much forwards, and join with the
pubis in a plate of bone (A) before reaching the
symphysis (/), which is very narrow and
formed by the pubes only. The pubes (b) of
the Mylodon are long and very slender, and
form an angle of about 160 with the ilia, the
apex of the angle being directed forwards, a
remarkable peculiarity, by which it differs, in
common with the Ant-eaters, from the other
Mammalia. The vertebro-Uiac angle is rather
acute, being about 125, and the ilio-ischial is as
small as 120, being very near the human angle.
Fig. 101.
Pelvis of the Mylodon robustus, posterior view ; show-
ing the ossification of the sacro-iliac and sciatic
ligaments.
The whole pelvis is remarkable for its
breadth and shallowness. The anterior outlet
is of an oval form, with the long diameters
antero-posterior. The posterior opening is
somewhat pentagonal, and, from the great
antero-posterior direction of the ischial rami
and the ossified sacro-sciatic junction, pre-
sents a flat level rim. The sacro-sciatic fora-
men (/) is comparatively small, but the obtu-
rator foramen (o) is large and oval.
The pelvis is one of the most characteristic
parts of the fossil Megatherium, as forming
the fulcrum of muscular forces of unusual
vigour. The sacrum is very narrow, and shorter
proportionably than in the Mylodon, and is
composed of five vertebrae, only the last being
broader transversely. There is no ankylosis
to the last lumbar vertebra.
The iliac wings are large and expanded,
with a concavity directed forwards, the ante-
rior superior spines overhanging the femurs,
and the external border very concave. They
are more massy than in the Mylodon, and
present no hook-like process on the crest.
The ischia are broad, blade-like, and massy ;
the tuberosities are not well marked, but
rounded and ankvlosed to the lower sacral
vertebrae, enclosing a small foramen, and
contributing, with the ankylosed ilia, to sup-
port the weight of the animal. Ilio-ischial
angle 125. The pubes are slender and very
oblique, and form, like the Mylodon, a reversed
ilio-pubic angle of about 155. The pubic
symphysis is narrow, and presents anteriorly
a rostrated projection. The acetabula are
large and near to each other ; the planes are
inclined from the perpendicular about 65.
The anterior outlet is oval, with long diameter
antero-posterior. The posterior has the long
diameter transverse. The obturator opening
is comparatively small. The whole pelvis
has a very massive appearance.
The pelvis of the other Edentata presents
the same general type as that of the Sloths.
In the Armadillo (Dasypus longicaudus] there
is a sacrum of nine vertebrae, the three upper
of which are ankylosed to the ilia, and the
sacral spines are coalesced in a crest. The
sacrum is narrowed to a remarkable extent
between its iliac and its sciatic portions, ex-
panding much in the latter part to meet and
coalesce with the ischia, with which it forms a
broad osseous plate in the site of the sacro-
sciatic ligaments. The oblique sacro-iliac ridge
is also well marked- The caudal bones are
numerous.
The ilia are long, strong, broad, and pris-
matic, and the alae are prolonged into broad
lamellar plates, which are ankylosed con-
tinously to the sacrum, and assist to support
the carapace. The ilia are much more ap-
proximated to each other than the ischia.
Lumbo-i/iac angle 155. The ischia are large,
broad, and considerably divergent, with broad
tuberosities prolonged dorsally to support the
shell ; coalescing in a broad plate with the
lower sacral pieces, and enclosing a moderately
sized sacro-sciatic foramen. The rami are at
right angles to the body of the ischia. The
ilio-ischial angle is marked, (145). The pubes
are slender and very obliquely directed back-
wards, making an ilio-pubic angle of 150;
and the symphysis is short, especially in the
Weasel-headed Armadillo, in which also the
ilio-pubic angle is smaller. (130). The pos-
terior pelvic outlet is much larger than the
anterior, from the greater eversion of the ischia.
In the Cape Ant-eater (fig. 102.) the sacrum
is composed of six pieces, with the spines (a)
coalesced, but leaving foramina between them,
and the last transverse processes (6) elongated.
Caudal bones numerous (fig- 102.).
The ilia are very thick and prismatic, and
more perpendicular to the spine, with the an-
terior and posterior borders thickened into a
strong ridge. The alae are concave externally,
the posterior superior spines (e) prolonged
dorsally, and ankylosed to the sacrum, and the
anterior superior (g), prolonged and curved
outwards and downwards. The ischia are
very long, expanding into a broad plate poste-
riorly (c), but do not touch the last sacral
vertebra. The ischial spines (i) are marked,
and the tuberosities present two tubercular
projections, one directed outwards, long and
sharp (&) ; and the other thicker, and directed
u 2
164
PELVIS.
florsally (/). The pubes (d) are directed
obliquely backwards with very short &ym-
physis (/), and the ilio-pectineal spine (//)
is very large. The pelvis is altogether massy
and large, with long sciatic notches and con-
siderable obturator foramina.
Fig. 102.
Pelvis of the Cape Ant-eater, side view.
In the great American Ant-eater, both the
ilia and ischia abut closely on the sacral trans-
verse processes, presenting a faint suture at the
line of junction. The pelvis is proportion-
ately smafler and lighter, and the processes and
spines much less marked than in the Cape Ant-
eater. The lumbo-Uiac angle in the Ant-eaters
is 140, the ilio-ischial 140 ; and the Hio-pubic
is reversed, and about 155.
The Manis possess pelves of the same ge-
neral heavy appearance as the American Ant-
eater. The ilia and ischia are closely approxi-
mated, but not ankylosed to the sacrum. The
symphysis pubis is short and not joined by the
ischia, and the pelvic openings comparatively
small.
In the foregoing Sloths and Edentata, and in
some of the Rodents, we have remarked the
tendency of the anterior symphysis to become
shorter and more imperfect by the absence of
median union of the ischia, and that this is
accompanied by a corresponding increase of
the bond of union between the sacrum and
ilio-ischian elements of the pelvis, by a closer
approximation or ossification of their uniting
ligaments, to give greater firmness to the
pelvis as its anterior connection fails.
In the Insectivora and Bat tribe, this separa-
tion of the innominate bones is increased, and
the pubes also fail altogether, in many in-
stances, to meet in the median line. By the
classification of animals according to their
pelvci development, which is here adopted,
these tribes are placed much lower than their
general osteology allows, in the general classi-
fication commonly given by authors, and
are aliied more closely to the Bird type in
their pelvic formation.
Of the Insectivora, the Hedgehog presents
the least pelvic departure from the common
mammalian type. The sacrum is narrow and
triangular, and composed offour vertebrae, three
of which articulate with the ilia. The ilia are
thin and elongated, and placed on the spine
at an angle of 130. The ischia are slender,
projecting above the level of the sacrum, but
not touching it ; and the rami are long and
slender, and enclose with the pubes large
obturator foramina. The pubes are long,
slender, and obliquely directed, making an
ilio-pubic angle of about 150. The'symphysis
is very short, and the pelvic outlets large, with
the long diameters antero-posterior.
In the Tnpaia, one sacral vertebra only, out
of three, unites with the ilia, and there is a good
sized symphysis pubis, as is also seen in the
Tenrecs. In the genus Desman two sacral ver-
tebras articulate with the ilia and one with the
ischia; and I\\Q pubes are very obliquely placed
on the ilia, and, according to Blainville, are
placed, anteriorly, rather in contiguity than
in symphysis, giving to the pelvis very much
of the appearance of that of the Ostrich. In