MARSUPIALIA. 
uch was by the mouth of the mother. Her 
fore-paws, in this case, would be used, not 
for the transport of the young, but for keeping 
the mouth of the pouch open for its reception, 
it being deposited therein by the mouth, and so 
held over a nipple until the mother had felt it 
grasping the sensitive extremity of the nipple. 
This means of removal is consistent with 
analogy ; dogs, cats, mice, all transport their 
young from place to place with the mouth. In 
the case of the kangaroo, it may be supposed 
that the foetus would be held by the lips only, 
not the teeth, on account of its delicate con- 
sistence. Whether this theory, suggested by 
witnessing the actions of the mother after an 
artificial separation of the Marsupial fetus, 
be correct, must be confirmed by actual obser- 
vation. There is no internal passage from the 
uterus to the pouch :—the mouth of the vagina 
cannot be brought into contact with that of the 
ian either by muscular contraction in the 
iving or by any force of stretching in the dead 
kangaroo :—as the young was proved by the 
result of this experiment not to have the power 
of itself to regain the nipple, @ fortiori we 
may conclude that it could not transfer itself 
from the vulva to the interior of the pouch and 
to the apex of the nipple :—the fore-paws of 
the Kangaroo would not so effectually protect 
the tender embryo from the external air as the 
mouth, nor so safely ensure its passage to the 
pouch, notwithstanding that they are adroitly 
used in grasping objects, being similar, in 
respect of the extent and freedom of motion of 
the digits, to the fore-paws of the Rodents. 
After the mother had rested quietly for a 
short time, we again examined her, but found 
the young one still detached, moving more 
vigorously than before. On an examination 
two days afterwards the marsupium was found 
empty: the young one had died and had pro- 
bably been removed by the mother. 
Thus the period of uterine gestation, the 
condition of the new-born young, and the pro- 
bable mode of its transference to the nipple 
being determined in the genus Macropus, it 
next remained to be determined how the embryo 
was nourished in utero. The means of giving 
the required solution were shortly after afforded 
by specimens of the impregnated uterus, trans- 
mitted to me by Mr. George Bennett, Captain 
Grey, and Dr. Sweatman. The first was of the 
Macropus major, nearly two-thirds of uterine 
gestation having been completed ; the second 
was of the Macropus penicillatus, at about the 
same or somewhat earlier period of gestation ; 
the third exhibited the uterine foetus at nearly 
the completion of that period of its existence. 
Before, however, giving the summary of what 
I have elsewhere* recorded respecting the 
uterine development of the Marsupialia, a de- 
scription of the ovarian ovum must be pre-. 
mised. 
In the Kangaroo this part agrees in all essen- 
tial points with the observed ovarian ova of 
placental Mammalia: the main moditication 
* Proceedings of the Zool. Society, 1833, Philos. 
Trans. 1834. 
323 
is the greater proportion of vitelline fluid and 
globules, and the smaller proportion of fluid 
between the external membrane of the ovum 
(vitelline membrane) and the ovarian vesicle, 
or lining membrane of the ovisac. 
Ina female Macropus Parryi, the ovum from 
the largest ovisac of the left ovarium measured 
wth of a line in diameter, the germinal vesicle 
risth of a line in diameter. 
We are at present ignorant of the changes that 
take place in the development of the ovum 
between the period of impregnation until about 
the twentieth day of uterine gestation. At this 
time, in the great Kangaroo ( Macropus major ), 
the uterine fetus (fig.138) measures eight 
lines from the mouth to the root of the tail; 
the mouth is widely open (fig. 141); the 
tongue large and protruded; the nostrils are 
small round apertures; the eyeball not yet 
wholly defended by the palpebral folds; the 
meatus auditorius externus is not provided with 
an auricle; the fore-extremities are the largest 
and strongest ; they are each terminated by five 
well-marked digits ; those of the hind legs are 
not yet developed; the cervical fold of the 
mucous layer or the branchial fissure is still 
unenclosed by the integument. The tail is 
two lines long, thick and strong at the com- 
mencement; impressions of the ribs are visi- 
ble at the sides of the body; the membranous 
tube of the spinal marrow may be traced 
along the back between the ununited elements 
of the vertebral arches ; posterior to the um- 
bilical chord there is a small projecting penis, 
and behind that, on the same prominence, 
is the anus. This foetus and its appen- 
dages were enveloped in a large chorion, 
puckered up into numerous folds, some of 
which were insinuated between folds of the 
vascular lining membrane of the uterus, but 
the greater portion was collected into a 
wrinkled mass. _ The entire ovum was re- 
moved without any opposition from a placental 
or villous adhesion to the uterus. The chorion 
(a, a, fig. 141) was extremely thin and lacera- 
ble; and upon carefully examining its whole 
outer surface, no trace of villi or of vessels 
could be perceived. Detached portions were 
then placed in the field of a microscope, but 
without the slightest evidence of vascularity 
being discernible. The next membrane, whose 
nature and limits will be presently described, 
was seen extending from the umbilicus to the 
inner surface of the chorion, and was highly 
vascular. The foetus was immediately enve- 
loped in a transparent amnios. 
On turning the chorion away from the foetus, 
it was found to adhere to the vascular mem- 
brane above-mentioned, into w the um- 
bilical stem suddenly expanded. With a slight 
effort, however, the two membranes could be 
separated from each other, without laceration, 
for the extent of an inch; but at this distance 
from the umbilicus the chorion gave way on 
every attempt to detach it from the internal 
vascular membrane, which here was plainly 
seen to terminate in a well-defined ridge, formed 
by the trunk of a bloodvessel. 
When the whole of the vascular membrane 
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