time we may suppose, that the European limestones were formed in deep water, out of the reach of such calcareous deposites; and, therefore, consists entirely of shells.

Beds of shells formed by sea currents. But the great difficulty on this subject, is to conceive how such vast beds of organic limestone could have been formed of shells, without requiring millions of years for their growth. It was in consideration of this subject, that the Editor of the Quarterly Review, vol. xlii. (1829,) declares that the earth, instead of being millions of years, was millions of ages in forming.

The idea of geologists, who require so much time for these formations, appears to be, that the shells must of necessity have grown and perished in the exact places where their remains are now found, and that one generation must have lived on the remains of the other, in succession, until they formed the masses which we now see.

But there is not the slightest probability from the very nature of the case, that this was the mode in which these masses were formed. For, in many instances, we find them of considerable thickness in the centre; gradually becoming thin towards the edges, and of small extent; the very form, a mass of shells would have assumed had they been swept together by currents of the sea, and quite different from that which would have been produced, had they lived and died on each other. In the latter case, there is no reason why these masses should ever assume the form of hills, but, on the contrary, we should naturally suppose that in similar climates, and under the same circumstances, these testacea would increase as rapidly in one place as in another, and thus, that the strata they formed would be widely extended, and every where of the same thickness. Whereas, we find that beds of shells in the same vicinity, are often entirely insulated. Besides, many of these shells are known to be such as burrow in the sand and mud, and unless we suppose that these masses were formed by currents, we are under the necessity of believing, that such species forsook their natural haunts for the purpose of living and dying on the remains of their ancestors.

Besides, we know from the reports of naval men, who have been employed in surveying sea coasts in various countries, that beds of shells are constantly forming at

the bottom of the ocean, by the agency of currents, and sometimes at the depth of several thousand feet.

In the strait of Gibraltar, Capt. Smyth found shells at the depth of 950 fathoms, carried thither probably from comparatively shallow parts, by the strong current which flows through that channel. Capt. Vidal detected on the coast of Ireland, large quantities of shells at depths vary. ing from forty-five to 190 fathoms; and also in the same region a bed of fish bones extending two miles along the bottom of the sea, in eighty and ninety fathoms of water.

"Analogous formations," says Mr. Lyell, "are in progress in the submarine tracts extending from the Shetland Islands to the North of Ireland, wherever sounding can be procured. A continuous deposite of sand and mud, replete with broken and entire shells, echini, &c., has been traced for upwards of twenty miles to the eastward of the Faroe Islands, usually at the depth of from forty to 100 fathoms. In one part of this tract, fish bones occur in extraordinary profusion, so that the lead cannot be drawn up without some vertebræ being attached. This bone bed,' as it is called by the surveyors, is three miles and a half in length."*

The sea, undoubtedly, is almost every where forming beds of shells, by its currents in the same manner, and which in the course of a few centuries at longest, might reasonably be supposed to form stratified organic rocks, of hundreds of feet in thickness, cemented by the sedi mentary matter of rivers, with which the sea abounds on every coast. How then does it become necessary to allow ages of time for these formations.

The objection that has been brought against the theory of accumulation by currents, in the fact that many, or most of the shells still retain their sharpest angles, and most delicate parts uninjured, will be found of little weight when the circumstances are considered.

All shells will swim in water of sufficient depth, even after the animal has perished; and, under water of moderate depth, most species will float to great distances without the slightest injury. In several extinct species, which are found in the greatest abundance in limestone, the specific gravity of the shell was so near that of water,

*Vol. iii. p. 295.

that the animal had the power of raising or sinking itself at pleasure, probably by drawing in or throwing out a little of that element. Such were the many-chambered univalves already described and figured, the Nautilus, the Ammonites, and the Orthoceratites.

On the coast of England, in places where the current is so swift as to remove deep channels in the regular strata, and where rocky masses are often precipitated into the sea, there still live fragile shells and tender zoophytes, (corals and sponges,) in abundance, and in the midst of these violent movements.*

There is, therefore, we conceive, no difficulty in supposing, that shells might have been swept into beds from great distances, and still retain their finest lines and sharpest angles. Those which we find on beaches, where they have been constantly exposed to the friction of the sand, by the motion of the surf, bear no analogy of circumstances to those which remain in deep water.

Vast number of shells created. Under the hypothesis, that all secondary limestone has originated from living existences, and has been formed within a few thousand years, we must believe that vast numbers of these tribes were originally created, and that they have multiplied with great rapidity.

With respect to the number created, we are bound to believe that it was peculiarly great, from the terms of the history, for in no other instance is the same language employed. "Let the waters bring forth abundantly the moving creature," are the words of the command; and we shall see, in this case, a coincidence between the scriptures and the facts of geology and natural science, not before noticed.

As the terms of the command were general, ("Let the waters bring forth,") so must have been the effect; and we are therefore bound to believe, that this creation was not confined to particular portions of the sea, but that the waters in all parts of the earth brought forth an abundance of living creatures, and we need not stop to show that shells are included in this creation.

* Lyell's Geology, vol. i. p. 308.

Rapid progress of Conchology. There is reason to believe, that no department of nature is so abundantly supplied with species and varieties, as Conchology. It is true that there are, at present, more known species of plants than of shells, but the facility of collecting the former, together with the connection which botany has with medicine and domestic economy, makes it the more interesting and important science. Yet, it is believed that the comparative number of new species of shells, recently discovered, have been much greater than those of plants.

Perhaps some judgment may be formed of the progress of conchology, and the vast number of species which probably still remain to be discovered, by comparing the system of Linnæus with that of Lamarck. The former naturalist describes only thirty-six genera of shells, while the latter has determined and described 250 genera; and many new species have been discovered within the few years since the last work was written. Hence we may infer, that conchology is only in its infancy, at least with respect to the number of species known, and that it is probable, thousands of species if not of genera, still remain to be discovered in this department

of nature.

The number of known species belonging to some of the Linnæan genera are already very numerous, and new ones are almost every day accumulating. Of the genus Conus, Mr. Mawe names 170 species, and of the genus Voluta 200 species, and of each of these, there are numerous varieties.*

The subject of fossil conchology has still more recently attracted the attention of naturalists, but when we come to examine the catalogues of extinct species, which have already been determined, and consider that these have been discovered in those few places on the earth, where excavations have been made, chiefly for economical purposes, we cannot avoid being struck with an idea of the vast multitude of these species which the earth contains, the most of which still remain unknown.

Of the genus Ammonites, there have been determined and named 159 species, not one of which are now sup

* Mawe's Conchology, p. 87–105.

Of the genus Cerithium,

posed to be in the living state.* seventy fossil species are known, and of the genus Terebratula, fifty species have been determined, and catalogues of both given.t

In the oolitic limestone alone, there has been already discovered, and described, not less than 1000 species of shells, a great proportion of which occur in England.‡ In the Paris basin, the species long since enumerated, amounted to 1200, and an equal number have been found in the more modern formations of the subapennine hills.§ Now when it is considered that these investigations have only just commenced, and that the parts of the earth which have been examined are mere points, when compared, even with the secondary portions of the whole; when we remember, also, that most of the recent species known, have been picked up along the shores, rather by accident, than through any scientific design; and that the wide oceans, the distant reefs, and the deep waters are still unexplored, and, when we compare these circumstances with that of the number of shells already known, we cannot but conclude, that there must be in the earth, and in the sea, thousands, perhaps millions, of species, which the eye of man has never yet seen.

From this vast number of species which it is thus certain have existed, or do still exist, we are led to see the propriety of the peculiar language, which Moses employs with respect to the first act of the fifth day's creation; for since all these species were commanded into being at that time, the term abundantly, as applied to these animals, and these exclusively, has a literal and appropriate meaning.

It has been shown under the article, "Change of Climate," that the temperature of the earth was formerly much greater than at present, and it is well known, that shells of the same tribes, increase in size, in some proportion to the heat of the climate, where they are found. It is also a general law, that animals multiply most rapidly in hot climates. It may, therefore, be fairly inferred, that much larger quantities of organic limestone would have

* De La Beche, Manual, p. 364. See Parkinson's Fossil Organic Remains. De La Beche's Catalogue, Manual, p. 323–369. § Lyell's Geology, vol. i. p. 151.