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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 la
justice de nos theories zoologiques； puisque le vrai cachet
d'une theorie est sans contredit la faculte qu'elle donne de
prevoir les phenomenes。〃
In the 〃Ossemens Fossiles〃 Cuvier leaves his paper just as it
first appeared in the 〃Annales du Museum；〃 as 〃a curious
monument of the force of zoological laws and of the use which
may be made of them。〃
Zoological laws truly； but not physiological laws。 If one sees a
live dog's head； it is extremely probable that a dog's tail is
not far off； though nobody can say why that sort of head and
that sort of tail go together； what physiological connection
there is between the two。 So； in the case of the Montmartre
fossil； Cuvier； finding a thorough opossum's head； concluded
that the pelvis also would be like an opossum's。 But； most
assuredly； the most advanced physiologist of the present day
could throw no light on the question why these are associated；
nor could pretend to affirm that the existence of the one is
necessarily connected with that of the other。 In fact； had it so
happened that the pelvis of the fossil had been originally
exposed； while the head lay hidden； the presence of the
〃marsupial bones；〃 though very like an opossum's； would by no
means have warranted the prediction that the skull would turn
out to be that of the opossum。 It might just as well have been
like that of some other marsupial； or even like that of the
totally different group of Monotremes； of which the only living
representatives are the Echidna and the
Ornithorhynchus。
For all practical purposes； however； the empirical laws of co…
ordination of structures； which are embodied in the
generalisations of morphology； may be confidently trusted； if
employed with due caution； to lead to a just interpretation of
fossil remains； or； in other words； we may look for the
verification of the retrospective prophecies which are based
upon them。
And if this be the case； the late advances which have been
made in palaeontological discovery open out a new field for such
prophecies。 For it has been ascertained with respect to many
groups of animals； that； as we trace them back in time； their
ancestors gradually cease to exhibit those special modifications
which at present characterise the type； and more nearly embody
the general plan of the group to which they belong。
Thus； in the well…known case of the horse； the toes which are
suppressed in the living horse are found to be more and more
complete in the older members of the group； until； at the bottom
of the Tertiary series of America； we find an equine animal
which has four toes in front and three behind。 No remains of the
horse tribe are at present known from any Mesozoic deposit。
Yet who can doubt that； whenever a sufficiently extensive series
of lacustrine and fluviatile beds of that age becomes known； the
lineage which has been traced thus far will be continued by
equine quadrupeds with an increasing number of digits； until the
horse type merges in the five…toed form towards which these
gradations point？
But the argument which holds good for the horse； holds good； not
only for all mammals； but for the whole animal world。 And as the
study of the pedigrees； or lines of evolution； to which； at
present； we have access； brings to light； as it assuredly will
do； the laws of that process； we shall be able to reason from
the facts with which the geological record furnishes us to those
which have hitherto remained； and many of which； perhaps； may
for ever remain； hidden。 The same method of reasoning which
enables us； when furnished with a fragment of an extinct animal；
to prophesy the character which the whole organism exhibited；
will； sooner or later； enable us； when we know a few of the
later terms of a genealogical series； to predict the nature of
the earlier terms。
In no very distant future； the method of Zadig； applied to a
greater body of facts than the present generation is fortunate
enough to handle； will enable the biologist to reconstruct the
scheme of life from its beginning； and to speak as confidently
of the character of long extinct beings； no trace of which has
been preserved； as Zadig did of the queen's spaniel and the
king's horse。 Let us hope that they may be better rewarded for
their toil and their sagacity than was the Babylonian
philosopher； for perhaps； by that time； the magi also may be
reckoned among the members of a forgotten Fauna； extinguished in
the struggle for existence against their great rival；
common sense。
FOOTNOTES
（1） 〃Discours sur les revolutions de la surface du globe。〃
Recherches sur les Ossemens Fossiles； Ed。 iv； t。i。 p。185。＇
（2） 〃On the Eclipses of Agathocles； Thales； and Xerxes；〃
Philosophical Transactions； vol。 cxliii。
End