208 Marsupiama. MAMMALIA Marsupialta. 
state, and transferred by the mother into her marsu- 
pium, there to be nurtured through the final stages of 
their foetal condition, in a manner to be immediately 
described. Intimately assoeiated with this external 
specialization of integument, we find the bones of the 
pelvis, sufiplementcd by two styliform elements, or 
marsupial trochlear bones, as they are more properly 
called. Both in the male and female important muscles 
are attached to these osseous appendages, which are 
firmly articulated to the anterior border of the pelvis by 
a broad connecting surface, bound down by interarticu- 
lar fibrous bands, like those observable in other pelvic 
synchondroses or ligamentous joints. The marsupial 
bones vary considerabl}’ in dilferent species, being 
elongated,- flattened, and curved in the wombat, and 
comparatively straight and narrow in Perameles. In 
the koala they are very large and scimitar-shaped, a 
(fig. 84); but ‘only one inch and a half in length in 
Myrmecobius. The ordinary abdominal muscles con- 
Fig. 84 
Pelvis and marsupial bones of Koala (Pliascolarctos cinereus). 
nected with these bones aid them in supj>oiting the 
marsupium and its contents, but a special muscle 
— analagous to the so-called “ cremaster” of the male 
— is developed in the female, whose function it is to 
expel the milk-secretion of the mammary glands when 
the young have become located in the ])ouch and duly 
attached to the teats. The mode of their connection 
with the long nipples is very curious ; as, in order to 
allow of respiratory action being carried on by the 
feetus in marsupio, it is clearly necessary that the milk 
should be conve 3 'ed directly into the stomach, without 
the chance of its blocking up the air passages ; and as 
yet — to take an exain])le — the little kangaroo can 
hardly display any involuntary functions, such as 
might regulate the flow of milk, and thereby, in con- 
nection with the ordinary reflex action of the larynx, 
obviate the necessity of anj^ special modification of the 
pharyngeal organs. To prevent choking, therefore, the 
windpipe is extended upwards to the soft palatal mem- 
brane, which, acting like a sphincter, embraces its 
patent outlet, bringing it into immediate contact, and 
also in continuation with the nasal passages. At the 
same time the teat of the mother is thrust far back in 
the mouth, and the injected milk flows freely down to 
the stomach, iirecisely in the same manner as the food 
of the porpoise, in the first instance, passes the pharynx 
by two passages into the gullet ! One can hardly 
refrain from comment on so remarkable a modification 
of structure destined to meet the exigencies of these 
interesting species ; a,nd as, perhaps, otir sentiments on 
this score may derive additional cogency when expressed 
in the language of an authority — who has contributed 
more than anj' other individual to the unravelling of 
the intricacies and significance of the marsupial struc- 
ture — we have little hesitation in inviting attention to 
Professor Owen’s comment, including additional details 
respecting this organization, as it occurs in the kan- 
garoo : — “ Thus aided and protected b_y modifications 
of structure, both in the system of the mother and its 
own, designed with especial reference to each others’ 
peculiar condition, and affording, therefore, the most 
irrefragable evidence of creative foresight, the small 
(iffspring of the kangaroo continues to increase, from 
sustenance exclusively derived from the mother, for a 
period of about eight months. During this period the 
hind legs and tail assume a great part of their adult 
proportions ; the muzzle elongates ; the external ears 
and eyelids are completed ; the hair begins to be 
developed at about tbe sixth month. At the eighth 
month the young kangaroo may be seen frequently to 
protrude its head from the mouth of the pouch, and to 
crop the grass at the same time that the mother is 
browsing. Having thus acquii-ed additional strength, 
it quits the pouch, and hops at first with a feeble and 
vacillating gait, but continues to return to the pouch 
for occasional shelter and supplies of food till it has 
attained the weight of ten pounds. After this it will 
occasionally insert its head for the purpose of sucking, 
notwithstanding another foetus may have been deposited 
in the pouch ; for the latter attaches itself to a difl'ei'ent 
nipple from the one which had been previously in use.” 
Having advanced thus much concerning the most 
important features of the order, it only remains for us to 
notice very brief!}' some other minor characteristics. 
Speaking generally, it may be said that the numerous 
species which are thus linked together into one group, 
present very striking differences in their structure, and 
consequently also in their habits of living. These are 
for the most part indicated in the union of the skull and 
in the form of the teeth, of the two clavicles into a 
single furcular bone, and in the condition uf the cranio- 
dental ])eculiarities bearing a strict relation to their 
carnivorous and insectivorous propensities on the one 
hand, and to the mixed nature of their food and purely 
phytivorous habits on the other. In this respect alone, 
therefore, three or four, more or less, natural groups are 
presented to us. But it is not alone in the skeleton 
that such correlative peculiarities exist, as many scarcely 
less interesting deviations affect the brain, the circula- 
tory organs, the digestive organs, and its associated 
chylo-poietic viscera. Into these, however, it is not our 
]irovinco to enter ; and it must, therefore, suffice us to 
