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XXII. Outlines of a Classification of the Marsupialia. By Ricuarp Owen, Esq., F.R.S., 
&c., Hunterian Professor of Anatomy at the Royal College of Surgeons. 
Communicated January 8th, 1839. 
THE present essay is offered as an introduction to a series of observations tending to 
establish the species of Marsupial animals on anatomical, and principally on osteological 
characters. 
Whoever has been led to compare an unknown or doubtful Marsupial with the brief 
notices of a few external peculiarities, on which many nominal species have been 
founded, must have felt the want of more detailed and surer grounds of comparison. 
M. Temminck, in his Monograph of the genus Phalangista, has left nothing to desire 
in this respect ; and the figures of the crania and other parts of the skeleton with which 
his zoological descriptions are illustrated, have been of essential service in establishing, 
and enabling subsequent naturalists to recognize, the species of that subdivision of the 
genus which is distributed chiefly through the Indian Archipelago. 
The philosophic use which the celebrated naturalist of Leyden has made of the rich 
collections at his disposal is well worthy of imitation ; and I propose to apply the mate- 
rials which I already possess, and those that may hereafter be afforded me by the en- 
lightened travellers and collectors in Australia, to illustrate in a similar manner the Mar- 
supial genera which are peculiar to that continent. 
Before, however, pointing out the particulars by which the skeleton of one species 
differs from another, some general remarks on those osteological peculiarities which 
characterize the Marsupialia as a distinct group of Mammals, seems to be called for ; and 
to these general observations I here premise an outline of a classification of the Marsu- 
pial animals which has had its origin in an endeavour to express in general propositions 
the more important facts relative to their organization. 
As the Australian continent, the great metropolis of the Marsupial quadrupeds, still 
remains but very partiaily explored ; and since new species and even genera of Mar- 
supials continue at each expedition to reward the researches of the scientific traveller ; 
and as moreover the recovery of two lost but distinct genera from the ruins of a former 
world makes it reasonable to suppose that other types of Marsupials remain still hidden 
in the crust of the earth, it can hardly be expected that the zoologist should be able to 
arrange in a natural series, with easy transitions according to the order of their affini- 
ties, the few and diversified forms of this implacental subclass which are now known, 
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