Abdominal muscles, Phatangista vulpina. 
supial bone (a), over which its strong inner 
tendon is spread ; the external oblique becomes 
aponeurotic at a line continued from the mar- 
supial bone outwards, with a gentle curve, to- 
wards the anterior extremity of the ilium; and 
in the opposite direction, or inwards, the car- 
neous aes of the external oblique terminate 
in an aponeurosis along a line parallel with the 
oblique outer margin of the pyramidalis; the 
fascia continued from the latter boundary of the 
fleshy fibres passes over, or dermad of, the so- 
called pyramidalis, and meets its fellow at the 
linea alba ; it is strictly analogous to the anterior 
layer of the sheath of the rectus in ordinary Mam- 
malia. It is seen reflected from the pyramidalis, 
at b, fig.112. The aponeurosis continued from 
the external and inferior boundary of the car- 
neous fibres divides as usual into two distinct 
portions; one, tion S-RbDe to the internal or 
mesial pillar of the abdominal ring, spreads its 
glistening fibres, as above described, over the 
dermal surface of the marsupial bone (c), to 
which it closely adheres: the other column (d) 
contracts as it descends obliquely inwards, 
forms, like Poupart’s ligament, the upper boun- 
dary of the space through which the psoas and 
iliacus muscles and femoral vessels and nerves 
escape from the pelvis, and is finally inserted, 
thick and strong, into the outer end of the base 
of the marsupial bone. 
This bone is so connected with the pubis 
that its movements are almost limited to di- 
rections forwards and backwards, or those con- 
cerned with the dilatation and diminution of 
the abdominal space; the contraction of the 
abdominal muscles must draw the bones in- 
wards so as to compress the contents of the 
abdomen, and so far as the connections of the 
bone permit, which is to a very trifling degree, 
the external oblique may draw it outwards to- 
wards the ilium. 
In some Marsupials, as the Koala, the trice 
adductor femoris sends a slip of fibres to the 
external angle of the base of the marsupial 
bone, and would more directly tend to bend 
that bone outwards. 
The upper or anterior fibres of the internal 
MARSUPIALIA. 
A to the seer part of the acetabulum : these ear- 
oblique have the usual origin; the lower ones 
(e) arise fleshy from the outer and anterior — 
spine of the ilium, and for an inch along an 
aponeurotic chord extended from that process” 
neous fibres pass inwards, and slightly up 
and terminate close to the outer margin of the 
rectus, where they adhere very strongly to the” 
transversalis, but give off a separate sheet of 
thin aponeurosis which is lost m the cellular 
sheath of the posterior rectus. - # 
The fleshy fibres of the transversalis abdomi- 
nis (f)) are closely connected by dense cellular 
tissue with those of the internal oblique ; they” 
are arranged in finer fasciculi, and have, as 
usual, a more transverse direction; they - 
nate along the same line as those of the internal 
oblique in an aponeurosis (g), which is con 
tinued along the inner or central surface of th 
—_ rectus to the median line. The le 
oundary of the Heshy fibres of the transve 
is parallel with the line extended trans I 
between the anterior extremities of the ilia; 
fascia, less compact than an aponeurosis, is con- 
tinued downwards from this margin, ive- 
lopes the cremaster and the constituents of the’ 
spermatic chord, as they pass outwards and 
forwards beneath the lower edge of the inte 
oblique. 
The pyramidalis (h) arises from the 
inner or mesial margin of the marsupial bone; 
from which the fibres diverge, the lower ones 
passing transversely across the interspace of the 
bones, and meeting at a very fine raphé, or 
linea alba ; while those fibres from the anteri ie 
ends of the marsupial bones gradually exchang ez 
their transverse direction for one obliquely for-— 
wards. The breadth of each pyramidalis oppo-— 
site the upper end of the marsupial bone is 
more than an inch, the thickness of the muscle — 
one line. Ls 
The rectus abdominis or posterior re 
(i) comes off from the pubis along the inner 
pet of the strong ligamentous union of t 
road base of the marsupial bone, and 
pands as it ascends until it attains the level 
the ensiform cartilage, when the rectus dimi= 
nishes as it is inserted into the sternal extre= 
mities of the ribs reaching to the manubrium 
sterni and first rib in the Dasyures, as in the 
cats. 
The slight indications of tendinous inter> 
sections which were noticed in this dissection 
were confined to the posterior or central super 
ficies of the muscle; the first extended o 
half-way across from the outer margin. 
The cremaster (k), in the Phalanger and 
Opossum, is not a fasciculus of fibres simply 
detached from the lower margin of the interna 
oblique or transversalis, but arises by a narrow — 
though strong aponeurosis from the iliur > 
within and a little above the lower boun of 
the internal oblique, with the fibres of whi 4 
the course of the cremaster is not parallel; it 
might be considered as a part of the trans- — 
versalis, but it is separated by the fascia above 
mentioned from the carneous part of that mus= 
cle. Having emerged from beneath the margin” 
of the internal oblique, the cremaster escapes 
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