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. It expresses the ex

:

istence of swarms of animals,' of forms with which we are unacquainted, and it assures us of the evidence of their existence in fossiliferous rocks many miles thick, if only we could find them. But what will Mr Darwin place below the basis of the Silurian rocks? after the clay-slate system, the mica-schist system, and the gneiss system, what other formation shall we name? where between these and the granite will be room for his 'somewhere?' If the granite be not the general floor on which all the oldest formations rest, it is somehow or other very inconveniently near them, and by its position and appearance in all parts of the world has frequently suggested the suspicion that it is the ubiquitous substratum. Thus speaks Humboldt on this subject.

What we call the older Silurian strata are only the upper portions of the solid crust of the earth. The eruptive rocks which we see breaking through, pushing aside, and heaving up these, arise from depths that are ininaccessible to us; they exist, consequently, under the Silurian strata, composed of the same association of minerals which are familiar to us under the name of granite, augite, and quartz porphyry, at the points where, by breaking through, they become visible. Resting on analogies, we may safely assume that that which at one and the same time fills exclusive fissures in the name of veins, and bursts through the sedimentary strata, can only be an offset from an inferior bed. The active volcanoes of the present day carry on their processes at the greatest depths; and from the strange fragments which I have found included in streams of lava, in different quarters of the globe, I also hold it as more than probable that a primordial

granite-rock is the foundation of the great systems of stratification which are filled with such variety of organic remains' (Cosmos, i. 305).

How great would have been the surprise of Humboldt to hear of this other additional crust of the earth which had been accumulated somewhere,' between the earliest non-fossiliferous rocks and the granite.

But the Theory has other difficulties to surmount in confronting geology, and these the author has himself stated: The abrupt manner in which whole groups of species suddenly appear in certain formations has been urged by several paleontologists, Agassiz, Pictet, Sedgwick, &c., as a fatal objection to the belief in the transmutation of species. If numerous species, belonging to the same genera or families, have really started into life at once, the fact would be fatal to the Theory of descent with slow modification through Natural Selection. But we continually overrate the perfection of the geological record, and falsely infer, because certain genera or families have not been found beneath a certain stage, that they did not exist before that stage. In all cases positive palæontological evidence may be implicitly trusted, negative evidence is worthless, as experience has so often shown' (327).

Now this passage, as it clearly states the antagonism of geological science to Mr Darwin's system, is of the highest importance, for it amounts to this, that if that system is true, geology, as now established, is false, and that the deductions of palæontologists must be cancelled. If we overrate the evidence of geology, then the estimate of its value as a teacher is erroneous, and we must, according to this proposition, consider that the information obtained by