We do not even perceive how it can well be said, that even land animals did not exist in those most early states of the globe of which we have any evidence. It is not a proof of their non-existence that their remains do not occur in rocks ; it is even doubtful if we can, in any case, presume on it from such negative evidence. But to judge rightly of that, it is proper to inquire how the fact now stands with regard to the more recent deposits of the remains of land animals.
With the exception of a few found in particular places, in caverns and fissures, and of those that occur in the equally partial fresh-water deposits, the remains of quad rupeds or of land animals in general are found, as might be expected, in the alluvial strata of the dry land. If we examine that which is now taking place on the surface, we do not see how it can ever have been otherwise. The action of rivers deposits under the sea those materials which are the germs of future strata; but, except in some casual instances from occasional floods, they do not carry with them the carcasses of land animals. It is scarcely to be expected that, should the present bottom of the sea hereafter become elevated, so as to form the rocky bed of a new dry land, future geologists should find the skeletons of such animals imbedded in these rocks. And, in such a case, as it is equally certain that marine remains would predominate, the same fallacious conclusion might here after be drawn respecting that globe which we now in habit, and which we know to be swarming with terrestrial animals of a thousand species. " To render the petrifaction or preservation of animal mains successful, if we may use such an expression, these must die where they lived, and be preserved where they died. Hence it is easy to understand why crocodiles, or other amphibious creatures, should still be preserved in rocky strata of considerable antiquity; because, dying under the water, they were easily inclosed and secured from de struction. It by no means follows that others did not exist on the dry land at the same time; since nothing but a flood of some peculiar nature could be expected to have trans ported the materials of the entire skeleton in a perfect state. For reasons not far different, we have no great cause to expect even detached bones; as it is known, no less from the peculiar evidence afforded by the caverns formerly mentioned, than from other facts, that animals have peculiar choices for the places of their death; while the circumstances under which they might have been washed into the sea by rivers, even in a detached state, must have occurred so rarely as not to vitiate this sup position of their possible existence even at those periods.
It is not necessary to extend these remarks further, as to the general question that respects the increase of spe cies, or of animals of a more perfect organization, in the later periods of the earth. We can neither prove it, nor can we disprove it, absolutely ; and it must be left open to the imagination or affections of those who delight in spe culative and interesting questions.
As to the bare facts themselves, even admitting them their full weight, undisturbed by all collateral considera tions, they prove little or nothing, up to a certain point at least, respecting a gradual amelioration of the species or of the organization of animals. Any one who will take the trouble to examine even the scanty list at the end of this article, will find corresponding animals in the most ancient and in the most recent strata; always excepting the land animals, respecting which enough has already been said. Thus, ma,dreporites, orthoceratites, belemnites, and terebratulx, occur equally in the lowest red sandstone, and in the far distant chalk ; nay, what is much more in point, many of the genera found in the still more ancient strata, as in the argillaceous primary schist, such as echini, ammonites, chamites, tellinites, and others, occur equally in almost every one of the superior strata. It would re quire a long list of generic and specific names to point out the whole of these resemblances; but to give such a comparative view would be only to add to evidence that re quires no addition. It is sufficient that not a shadow of proof can be adduced in support of this notion of the gradual improvement of species, and that all our experi ence is, on the contrary, against it. The list hereafter given, scanty as it is, will serve to satisfy the warmest en thusiast respecting the fallacy of this opinion.