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