be authoritatively answered whether the base-rocks of the Silurian system were antecedent to life in our planet.

Mr Darwin, on the contrary, authoritatively affirms that it is indubitable that life swarmed in eras immensely more ancient than the lowest Silurian strata.

Between two such statements reconciliation is impossible. After the basal rocks in ascending order we come to the lower Silurian, and there we find the protozoa, the fucoids, the first form of sponges, palæospongia, graptolites, supposed to be compound animals of the Zoophyte order, and some mollusca. Of these ancient forms, some of which 'scarcely deserve the name of animal,' the Trilobite is the most interesting, a crustacean of tripartite form, and interesting for its nicely jointed and curious shell, and its elaborate eye.

All the fossils of the Silurian* system are eminently marine, and consist of species and genera of Zoophytes, radiata, mollusca, annilids, and crustacea. It is only towards the close of the Silurian era that any fishes appear, the first vertebrated animals. They are found in the uppermost verge of the system, or in beds which are by some considered as the basis of the Old Red Sandstone.

*As yet we have no indication whatever of a terrestrial fauna in the Silurian system; and the accumulating evidence of recent research rather tends to dispel the hope of ever finding, in true Silurian strata, any of the higher manifestations of vertebrate existence.'-Advanced Text Book of Geology, p. 159.

'It is a remarkable fact that the most sedulous research in many parts of the world has failed to discover the trace of any vertebrate animal in the lower division of the Silurian system. All the marine animals from Zoophytes to crustaceans, and which probably amount to more than 1000 species, already known, belong to invertebrated classes, and no true fish has yet been discovered. The name Silurian marks, therefore, the first series of fossiliferous deposits, throughout the great mass of which no vertebrated animals have been anywhere discovered.'--Murchison.

205-40.

Siluria,

The earliest good evidence which has been obtained of a vertebrate animal in the earth's crust is a spine of the nature of the dorsal spine of the dog-fish, and a buckler like that of a placoganoid fish, in the most recent deposits of the Silurian period, in the formation called the upper Ludlow Rocks' (Owen, 119).

We have then the predominance of the sea proved to us by this evidence, and of a sea sustaining life, though that life was dissimilar to that which now prevails in the ocean; and below that we have the exhibition of a period in which no life has been discovered; and if geology teaches us any commencement it is here we must seek it. We cannot go beyond the evidence.

"The fossiliferous strata occupying the lowest place in the geological sequence, have been observed to pass, in almost every instance, by gradual and imperceptible changes into non-fossiliferous rocks, and for this reason, in addition to others, it has been thought probable either that the lowest strata were in reality the first beds deposited upon the earth, and that the animals whose remains are found in them were its first inhabitants, or at least that no fossiliferous rocks of an older date, if such exist, exhibit any important zoological changes, or contain species different from those with which we are already acquainted' (Ansted, 87.)

Now if the suspicion of some of our chief geologists should be correct, that the dawn of life begins with the lowest Silurian formation, or even near it (in the nearness of geological time), it is obvious that the Theory is confuted, and that its confutation is complete; for in these rocks we find several animal forms of independent existence, of different genera and different species, and there

fore it is impossible that so early in the appearances of life all these separate phases should have been produced by Natural Selection; they must be, according to that system, the remnants and traditionary representatives of eras almost infinitely distant from that time-or else they must have come into existence by some other method. But if all these preceding eras and preceding rocks be a dream, then those animals have come into existence not by Natural Selection, but by other means.

This of course Mr Darwin has foreseen and provided for. 'I cannot doubt that all the Silurian Trilobites have descended from some one crustacean, which must have lived long before the Silurian age, and which probably differed from any known animal' (332). Less than this could not be propounded in so critical a position of the Theory, for if the author had doubted' in this emergency, there would have been an end of the question. Here, however, we are again referred for proof to the invisible world, which no traveller can reach. There must have been, we are told, an ancestral crustacean long before the Silurian age, differing from all known animals, and from this the Trilobite must have descended! But what shall we say about this indescribable monster-unlike all known animals on land, or in sea, or in the regions of the air? It must indeed have been most wonderful, a chimera beyond the imagination of the poets, and of the same genus perhaps as the animal described by the showman, as having come 'from the undiscovered islands.' But, seriously, is not this abasing rather than elevating science to connect it with such speculations, which do not amount to the dignity of a conjecture, but must be ranked with those

fictions which have all the wildness without any of the inspiration of poetry.

'But,' says the Author, 'some of the most ancient Silurian animals, as the Nautilus, Lingula, &c., do not differ much from the living species, and it cannot, on my theory, be supposed that these old species were the progenitors of all the species and the order to which they belong, for they do not present characters in any degree intermediate between them. If, moreover, they had been the progenitors of these orders, they would almost entirely have been long ago supplanted and exterminated by their numerous and improved descendants' (id.). This, it will be observed, is a sort of private conversation of the author with himself, for what have we to do with the perplexities and exigencies of his Theory? Certainly according to that Theory, here is a sad trouble and discouragement, and the author tells us what it is. But it is only with the escape out of the difficulty that we are concerned, the breaks in the genealogy and the non-extermination of the improved families are his affair, not ours--on these deficiencies we only look on and smile, but again we beg leave to assure him that his appeal to a pre-Silurian world is no escape at all, and that he must on the battle-field of the lowest rocks yet discovered, either beat us or be beaten himself.

We have been told that the series of rocks which were antecedent to the Silurian, and took a longer time for their formation than all the rocks that have been subsequently deposited up to the present day, were 'SOMEWHERE accumulated.' Somewhere! did ever one word yet do service for so much as this somewhere?' It contains an unknown world, and ages incalculable. incalculable. It expresses It expresses the ex

upon others as they ought to be? If we appeal from what we see and know to that which can neither be seen nor known? if we set aside the evidence of the senses and substitute that of the imagination? If this be permitted within the precincts of science, what can be the limit to idle and profitless speculations? who after this need despair of advancing any theory however childish or preposterous? Supposing that some learned man felt it incumbent on himself to prove that there were giants in those days,' in the days near the beginning of things, and that he were to write a learned and ingenious book on the subject (such as an ingenious man might write on any theme), investing his hypothesis with an air of plausibility till he came to the evidence of geology. Here a barrier stops his progress; how does he surmount it? He tells us that if his Theory be true, it is indisputable, that in unknown ages long before the lowest Silurian formation, the earth swarmed with giants thirty feet high, and that their remains are to be found in those rocks which somewhere were formed' in that most distant epoch; but that we are not to be astonished at the actual deficiency of the proof, for we do but possess the last volume of geological record, all the previous ones having been irretrievably lost.

In what does this differ from Mr Darwin's process of reasoning? Surely in nothing but the Theory itself, which is far more difficult to be digested than the pre-Silurian giants.

There are occasions nevertheless when Mr Darwin can refer to the records of geology as affording most ample proof for any particular point he may have in hand. Geology,' says he, plainly tells us that small genera have in the lapse