Neither can the antiquity of beds be proved by the same reasons, unless we could also prove an absolute succession of species or genera in creation, and unless these recur rences were more constant and regular than they are, and than we have shown them to be in former parts of this essay. We might, besides, to these add many more ob jections to the probable value of this criterion, from gene ral considerations ; but it cannot be necessary. With respect to its value in minor cases, when the strata in one deposit, such as that of England, are to be identified, the objections diminish in number ; yet, even then, these proofs are not to he relied on, as must be evident from what was just stated respecting living colonies now in the surrounding seas. That which would not identify modern submarine strata of mud, must be expected to prove the identity of ancient strata of rock formed under the same circumstances. That it may afford occasional assistance will not be denied ; but, to use a wrong method of solving difficulties is not only to deceive ourselves, but to establish or confirm false theories, and to stop the progress of all useful investigation.
It is evident that, to prove the identity of an universal stratum, one species, or set of species, must have existed all over the ocean where its materials were deposited. To prove the correspondence of strata less universal, a more limited degree of the same improbability is required. To prove" that particular fossils determine the character and place of any particular stratum, every species, or set of species, should have changed with the superposition of a fresh stratum ; besides which, it should never either have pre-existed or re-existed. But it is surely unneces sary to add to these arguments, a priori, against this theory. We must, therefore, here drop the subject, and examine, in as few words as possible, by an enumeration of species and genera in particular strata, how the fact really stands. Conchologists, and those geologists who have studied this subject, will be at no loss to extend a comparison, which we shall render as distinct as is possible, consistent with the necessary brevity ; because a few deficiencies in the evi dence are sufficient to render the whole nearly, if not en tirely, useless ; and we need scarcely say how much we may be misled by thus trusting to what is imperfect or groundless.
The lias of France, Spain, Italy, and England, a stratum, or set of strata, well identified by their position with regard to the red marl, contains different fossils in these several countries. Echini are found from primary slate up to chalk, as are Tellinx, Turbines, and Chamx. The Be lemnite, which is common in the chalk of France and Ire land, is rare in that of England ; and the fossils of the chalk of Naestricht are' almost peculiar to it. The vegetable remains that are found in the clay of Sheppey do not occur in that stratum in other parts of England. a fossil not a little conspicuous, occur in the lias, in the Portland oolite, in the green sand of England, and in the blue clay. Crabs, which are found in one of the earliest secondary strata, to wit, the mountain limestone, also exist in the chalk, and in the London clay, as far asunder as they can well be. Madreporites, Entomolites, Pentaerinites, Patella', Ostrem, Ammonitx, Terebratulx, Gryphites, Pectines, A nomix, and numerous others, which it is super fluous to name, are found in nearly all the strata ; and so far is it from being true that there are even any predomi nant associations of these, that they occur intermixed in every possible manner, as will be more fully evinced in the general list hereafter given.
It seems, therefore, quite unnecessary to pursue this subject further ; since it must be sufficiently plain that the in question is worthless, or worse. We may, therefore, terminate these general observations, by sub joining the promised list of the fossil remains that have been found in particular strata, commencing from the lowest, and proceeding upwards to the alluvia. That list will serve, not only to complete this part of the subject, but as a point of reference for the names of many species which it was not thought necessary to enumerate in the various general illustrations that have been given of such parts of the history of fossil remains as were admissible within the plan and limits of this essay. If this list is not so full as might be expected, it is, at least, full enough for the present purpose ; nor could it easily be made more so, while so rapid a progress is making in this branch of na tural history.