arrived from the
quarries of Montmartre, the two halves of which contained the greater
part of the skeleton of a small animal. On careful examinations of
the characters of the teeth and of the lower jaw, which happened to be
exposed, Cuvier assured himself that they presented such a very close
resemblance to the corresponding parts in the living opossums that he at
once assigned the fossil to that genus.

Now the opossums are unlike most mammals in that they possess two bones
attached to the fore part of the pelvis, which are commonly called
"marsupial bones." The name is a misnomer, originally conferred because
it was thought that these bones have something to do with the support of
the pouch, or marsupium, with which some, but not all, of the opossums
are provided. As a matter of fact, they have nothing to do with the
support of the pouch, and they exist as much in those opossums which
have no pouches as in those which possess them. In truth, no one knows
what the use of these bones may be, nor has any valid theory of their
physiological import yet been suggested. And if we have no knowledge of
the physiological importance of the bones themselves, it is obviously
absurd to pretend that we are able to give physiological reasons why the
presence of these bones is associated with certain peculiarities of
the teeth and of the jaws. If any one knows why four molar teeth and an
inflected angle of the jaw are very generally found along with marsupial
bones, he has not yet communicated that knowledge to the world.

If, however, Zadig was right in concluding from the likeness of the
hoof-prints which he observed to be a horse's that the creature which
made them had a tail like that of a horse, Cuvier, seeing that the teeth
and jaw of his fossil were just like those of an opossum, had the same
right to conclude that the pelvis would also be like an opossum's; and
so strong was his conviction that this retrospective prophecy, about
an animal which he had never seen before, and which had been dead and
buried for millions of years, would be verified, that he went to work
upon the slab which contained the pelvis in confident expectation of
finding and laying bare the "marsupial bones," to the satisfaction of
some persons whom he had invited to witness their disinterment. As he
says:--"Cette operation se fit en presence de quelques personnes a
qui j'en avais annonce d'avance le resultat, dans l'intention de leur
prouver par le fait