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Devonian rocks, included in the great Siluro-Cambrian series, as these are older than the youngest of known formations 34 And this because otherwise life would
. start in Siluria far too high in the scale for the doctrine of natural selection. For its most typical form, the Trilobite (page 40), with its eye, in one species, of six thousand lenses, is as “fearfully and wonderfully made” as any crustacean in our present seas; and just on the upper edge of the system, ere it passes into the Old Red Sandstone, vertebrate life itself appears in the oldest of fossil fishes. On Mr. Darwin's hypothesis, life could not have begun thus: the ransacking of Siluria, east, west, north, and south---evidence which it would be an abuse of terms to call negative--bears witness that life did so begin. It is scarcely more evident, indeed, that
, life vanishes towards the base of the Cambrian rocks, than that man disappears ere we reach the Eocene. But our author's scheme has fresh exactions to make, and those of the most exorbitant kind, as we pass upwards from Siluria to the earth of to-day. Not only must we extemporise an imaginary fossil creation below, but we must interpolate vast piles of strata, and untold tribes of population, into the extant fossil creation above. The plea is, possible denudation. Now, although a consider
able stratum may be in part so destroyed, few geoloyists will concede the likelihood, if the protective dip be taken into account, of its being utterly swept away. In point of fact, whatever blanks have appeared to intervene between the various systems are being rapidly filled up and bridged over. This is true whether we apply the test of conformable transition, or that of continuity of organic remains. “Every year,” observes an unexceptionable witness, "adds to the list of links between what the older geologists supposed to be widely separated epochs.
From M. Pictet's calculations of what per-centage of the genera of animals existing in any formation lived during the preceding formation, it results that in no case is the proportion less than one-third, or 33 per cent. It is the Triassic formation,
. on the commencement of the Mesozoic epoch, which has received the smallest inheritance from preceding ages.” The other formations not uncommonly "exhibit 60, 80, or even 94 per cent. of genera in common with those whose remains are imbedded in their predecessor.” 35 Consistently with this, it must be noted that the three great divisions are not arbitrarily drawn. Proportion may be exemplified on any scale---on the scale of contracting poverty as on that of expanding plenitude.
Once, and again, and yet again, is there a dawn and a decay, a protracted dwindling and an exuberant revival, a lull and an outburst of life-giving energy, a trough and a crest of the creative wave. But the phenomenon
of poverty of fossils, at the transition epochs, infers no interruption to the continuity of deposits. Whatever be missing then, here, in the main, are the rocks themselves. M. Pictet and the Westminster Review being witnesses, here are the platforms of ancient nature, the shelves of the vast museum from Siluria to the Tertiaries, for the purposes of this inquest practically complete.
22. But are these platforms sufficiently peopled ? Are these shelves adequately filled ? Mr. Darwin insists that they are not. Natural selection depends for its aliment on myriads of groups, of which it is necessary to suppose that the ocean catacombs have failed to transmit a solitary member. Species immensely more ancient have been preserved by thousands, but of myriads of these more recent forms not one representative has been preserved. This is surely somewhat startling.
If anywhere, the received aphorism which refuses tu srparate what does not appear from what does not exist, seems to apply here. * There are many dark places in the field of human knowledge, which even the researches
ages may fail wholly to enlighten; but no one derives a right, from that circumstance, to people them with chimeras and phantoms. They belong to the philosophers of the future, not to the visionaries of the present."
Of land-animals, indeed, the chance of preservation is comparatively very small. Yet even their remains, when the species existed to have reinains to bequeath, are often found in extraordinary abundance. Witness the “ivory quarries” of Siberia, or the tusks representing hundred of mammoths fished up by the oyster-dredgers of the Norfolk coast, in the course of a few years of the present century. This even of landanimals ; but what of the giants of the sea ? Cetacean petrified teeth and skeletons are found in such quantities “as to constitute a great part of that source of phosphate of lime for which the Red Crag of the eastern counties of England is worked, for the manufacture of artificial manure.” 37 Now, keeping in mind, as we liave just been warned, that every year is tending to tone down those sharp demarcation-lines which parted sys
tem from system in the conception of the earlier geologists, let us steadily contemplate the gigantic reptileclass swarming multitudinous in the seas of the Oolite,
when the gigantic whale-class as yet was not; next survey the Cetacea, tempesting the waters of the Pliocene, when their reptile predecessors had passed away; and then calmly ask how natural selection will build us a bridge across the chasm? Did this agency convert a fish-lizard into a porpoise, or extemporize the faculty of giving suck to its young in a reptile "passing through the paths of the sea”? What scope for natural selection, bursting into the group of huge marine mammalia, amidst the monotonous and equable conditions of oceanic life? What creature led up to the whale or the dolphin? The saurians emerge on the geological stage, distinct, sharply defined : sharply defined they disap