ted as monsters and marvels. In one of the latest
examples, the inner splint-bone, answering to the second metacarpal of
the pentadactyle foot, supported phalanges and a terminal hoof
resembling the corresponding one in hipparion. And the pairing of horses
with the meterpodials bearing, according to type, phalanges and hoofs
might restore the race of hipparions.

Now, the fact suggesting such possibility teaches that the change would
be sudden and considerable; it opposes the idea that species are
transmuted by minute and slow degrees. It also shows that a species
might originate independently of the operation of any external
influence; that change of structure would precede that of use and
habit; that appetency, impulse, ambient medium, fortuitous fitness of
surrounding circumstances, or a personified "selecting nature" would
have had no share in the transmutative act.

Thus I have been led to recognise species as exemplifying the continuous
operation of natural law, or secondary cause; and that not only
successively but progressively; "from the first embodiment of the
vertebrate idea under its old ichthyic vestment until it became arrayed
in the glorious garb of the human form."

_III.--Extinction--Cataclysmal or Regulated_

If the species of palaeothere, paloplothere, anchithere, hipparion, and
horse be severally deemed due to remotely and successively repeated acts
of creation; the successive going out of such species must have been as
miraculous as their coming in. Accordingly, in Cuvier's "Discourse on
Revolutions of the Earth's Surface" we have a section of "Proofs that
these revolutions have been numerous," and another of "Proofs that these
revolutions have been sudden." But as the discoveries of palaeontologists
have supplied the links between the species held to have perished by the
cataclysms, so each successive parcel of geological truth has tended to
dissipate the belief in the unusually sudden and violent nature of the
changes recognisable in the earth's surface. In specially directing my
attention to this moot point, whilst engaged in investigations of fossil
remains, I was led to recognise one cause of extinction as being due to
defeat in the contest which the individual of each species had to
maintain against the surrounding agencies which might militate against
its existence. This principle has received a large and most instructive
accession of illustrations from the labours of Charles Darwin; but