Few facts are more remarkable in the history of the progress of human discovery, than that it should have been reserved almost entirely for the researches of the present generation, to arrive at any certain knowledge of the existence of the numerous extinct races of animals, which occupied the surface of our planet in ages preceding the creation of man. The rapid progress which, during the last half century, has been made in the physical sciences, enables us now to enter into the history of Fossil Organic Remains, in a manner which till within a very few years, would have been quite impracticable; during these years the anatomy of extinct species of Quadrupeds has been most extensively investigated, and the greatest of comparative anatomists has devoted much of his time and talent to illustrate their organization. Similar inquiries have been carried on also by a host of other enlightened and laborious individuals, conducting independent researches in various countries since the commencement of the present century; hence our knowledge of the osteology of a large number of extinct genera and species, now rests on nearly the same foundation, and is established with scarcely less certainty, than the anatomical details of those creatures that present their living bodies to our examination.

We can hardly imagine any stronger proof of the Unity of Design and Harmony of Organizations that have ever pervaded all animated nature, than we find in the fact established by Cuvier, that from the character of a single limb, and even of a single tooth or bone, the form and proportions of the other bones, and condition of the entire Animal may be inferred. This law prevails, no less universally, throughout the existing kingdoms of animated nature, than in those various races of extinct creatures that have preceded the present tenants of our planet; hence not only the frame work of the fossil skeleton of an extinct animal, but also the character of the muscles, by which each bone was moved, the external form and figure of the

body, the food and habits, and haunts, and mode of life of creatures that ceased to exist before the creation of the human race, can with a high degree of probability be ascertained.

Concurrent with this rapid extension of our knowledge of the comparative anatomy of extinct families of the ancient inhabitants of the earth, has been the attention paid to fossil Conchology; a subject of vast importance in investigating the records of the changes that have occurred upon the surface of our globe.

Still more recently, the study of botanists has been directed to the History of fossil vegetables; and although from the late hour at which this subject has been taken up, our knowledge of fossil plants is much in arrear of the progress made in Anatomy and Conchology, we have already a mass of most important evidence, showing the occurrence of a series of changes in vegetable life, coextensive and contemporaneous with those that have pervaded. both the higher and lower orders of the animal kingdom.

The study of Organic Remains, indeed, forms the ресиliar feature and basis of modern Geology, and is the main cause of the progress this science has made, șince the commencement of the present century. We find certain families of Organic Remains pervading strata of every age, under nearly the same generic forms which they present among existing organizations.* Other families, both of animals and vegetables, are limited to particular formations, there being certain points where entire groups ceased to exist, and were replaced by others of a different character.. The changes of genera and species are still more frequent; hence, it has been well observed, that to attempt an investigation of the structure and revolutions of the earth, with-out applying minute attention to the evidences afforded by

* E. g. The Nautilus, Echinus, Terebratula, and various forms of Corals; and among Plants, the Ferns, Lycopodiacea, and Palms...

organic remains, would be no less absurd than to undertake to write the history of any ancient people, without reference to the documents afforded by their medals and inscriptions, their monuments, and the ruins of their cities and temples. The study of Zoology and Botany has therefore become as indispensable to the progress of Geology, as a knowledge of Mineralogy. Indeed the mineral character of the inorganic matter of which the Earth's strata are composed, presents so similar a succession of beds of sandstone, clay, and limestone, repeated irregularly, not only in different, but even in the same formations,* that similarity of mineral composition is but an uncertain proof of contemporaneous origin, while the surest test of identity of time is afforded by the correspondence of the organic remains: in fact without these, the proofs of the lapse of such long periods as Geology shows to have been occupied in the formation of the strata of the Earth, would have been comparatively few and indecisive.

The secrets of Nature, that are revealed to us, by the history of fossil Organic Remains, form perhaps the most striking results at which we arrive from the study of Geology. It must appear almost incredible to those who have not minutely attended to natural phenomena, that the microscopic examination of a mass of rude and lifeless limestone should often disclose the curious fact, that large proportions of its substance have once formed parts of living bodies. It is surprising to consider that the walls of our houses are sometimes composed of little else than comminuted shells, that were once the domicile of other animals, at the bottom of ancient seas and lakes.

It is marvellous that mankind should have gone on for

* The same formation which in England constitutes the argillaceous deposites of the London Clay, presents at Paris the sand and freestone of the Calcaire Grossier; whilst the resemblance of their Organic remains proves the period of their deposition to have been the same, notwithstanding the difference in the character of their mineral ingredients.

so many centuries in ignorance of the fact, which is now so fully demonstrated, that no small part of the present surface of the earth is derived from the remains of animals, that constituted the population of ancient seas. Many extensive plains and massive mountains form, as it were, the great charnel-houses of preceding generations, in which the petrified exuviæ of extinct races of animals and vegetables are piled into stupendous monuments of the operations of life and death, during almost immeasurable periods of past time. "At the sight of a spectacle," says Cuvier,*" so imposing, so terrible as that of the wreck of animal life, forming almost the entire soil on which we tread, it is difficult to restrain the imagination from hazarding some conjectures as to the causes by which such great effects have been produced."

The deeper we descend into the strata of the Earth, the higher do we ascend into the archæological history of past ages of creation. We find successive stages marked by varying forms of animal and vegetable life, and these generally differ more and more widely from existing species, as we go farther downwards into the receptacles of the wreck of more ancient creations.

When we discover a constant and regular assemblage of organic Remains, commencing with one series of strata, and ending with another, which contains a different assemblage, we have herein the surest grounds whereon to establish those Divisions which are called geological formations, and we find many such Divisions succeeding one another, when we investigate the mineral deposites on the surface of the Earth. The study of these Remains presents to the Zoologist a large amount of extinct species and genera, bearing important relations to existing forms of animals and vegetables, and often supplying links that had hitherto appeared deficient, in the great chain whereby all animated

* Cuvier rapport sur le progrès des sciences naturelles, p. 179..

1

beings are held together in a series of near and gradual connexions.

This discovery, amid the relics of past creations, of links that seemed wanting in the present system of organic nature, affords to natural Theology an important argument, in proving the unity and universal agency of a common great first cause; since every individual in such a uniform and closely connected series, is thus shown to be an integral part of one grand original design.

The non-discovery of such links indeed, would form but a negative and feeble argument against the common origin of organic beings, widely separated from one another; because, for aught we know, the existence of intervals may have formed part of the original design of a common creator; and because such apparent voids may perhaps exist only in our own imperfect knowledge; but the presence of such links throughout all past and present modifications of being, shows a unity of design which proves the unity of the intelligence in which it originated.

It is indeed true that animals and vegetables of the lower classes prevailed chiefly at the commencement of organic life, but they did not prevail exclusively; we find in rocks of the transition formation, not only remains of radiated and articulated animals and mollusks, such as Corals, Trilobites, and Nautili; but we see the vertebrata also represented by the Class of Fishes. Reptiles have been found in some of the earliest strata of the secondary formations.* In the footsteps on the New Red sandstone, we have probably the first traces of Birds and Marsupialia. (See Pl. 26a. and 26'.) The bones of Birds occur in the Wealden formation of Tilgate forest, and those of Marsupialia in the Oolite at Stonesfield. (See Pl. 2. Figs. A. B.)

* E. g. In the Magnesian Conglomerate of Durdham Down near Bristol, and in the bituminous marl slate, (Kupferschiefer) of Mansfield in the Hartz.