great numbers of fossil Crustaceans, and also the remains of many fishes, and of Crocodiles, and aquatic Tortoises.

As the drifted seeds that occur in Sheppey seem to have been collected by the action of marine currents, the history of European vegetation during the Tertiary period, must be sought for in those other remains of plants, whose state and circumstances show that they have grown at no great distance from the spot in which they are now found.*

Conclusion.

The following is a summary of what is yet known, respecting the varying conditions of the Flora of the three great periods of Geological history we have been considering.

The most characteristic distinctions between the vegetable remains of these periods are as follows. In the first period, the predominance of vascular Cryptogamic, and comparative rarity of Dicotyledonous plants. In the second, the approximation to equality of vascular Cryptogamic, and Dicotyledonous plants. In the third, the predominance of Dicotyledonous, and rarity of

*The beautiful Amber, which is found on the eastern shores of England, and on the Coasts of Prussia and Sicily, and which is supposed to be fossil resin, is derived from beds of Lignite in Tertiary strata. Fragments of fossil gum were found near London in digging the tunnel through the London clay at Highgate. + The dicotyledonous plants of the Transition and Secondary

vascular Cryptogamic plants. Among existing vegetables almost two thirds are Dicotyledonous. The Remains of Monocotyledonous Plants occur, though sparingly, in each Period of Geological formations.

The number of fossil plants as yet described is about five hundred; nearly three hundred of these are from strata of the Transition series; and almost entirely from the Coal formation. About one hundred are from strata of the Secondary series, and more than a hundred from formations of the Tertiary series. Many additional species have been collected from each of these series, but are not yet named.

As the known species of living vegetables are more than fifty thousand, and the study of fossil botany is as yet but in its infancy, it is probable that a large amount of fossil species lies hid in the bowels of the earth, which the discoveries of each passing year will be continually bringing to light.

The plants of the First period are in a great measure composed of Ferns, and gigantic Equisetacea; and of families, of intermediate character between existing forms of Lycopodiacea and Coniferæ, e. g. Lepidodendriæ, Sigillariæ, and Stigmariæ; with a few Coniferæ.

Of plants of the Second period, about one third

formations present only that peculiar tribe of this class, which is made up of Cycades and Coniferæ, viz. Gymnospermous Phanerogamiæ.

are Ferns; and the greatest part of the remainder are, Cycadeæ and Coniferæ, with a few Liliaceæ. More species of Cycadeæ occur among the fossils of this period, than are found living on the present surface of the earth. They form more than one third of the total known fossil Flora of the Secondary formations; whilst of our actual vegetation, Cycadeæ are not one two-thousandth part.

The vegetation of the Third period approximated closely to that of the existing surface of the globe.

Among living families of plants, Sea weeds, Ferns, Lycopodiaceæ, Equisetaceæ, Cycadeæ and Coniferæ, bear the nearest relations to the earliest forms of vegetation that have existed upon our planet.

The family which has most universally pervaded every stage of vegetation is that of Coniferæ ; increasing in the number and variety of its genera and species, at each successive change in the climate and condition of the surface of the earth. This family forms about one three-hundredth part of the total number of existing vegetables.

Another family which has pervaded all the Series of formations, though in small proportions, is that of Palms.

The view we have taken, of the connexions between the extinct and living systems of the vegetable kingdom, supplies an extensive fund of

arguments, and lays open a new and large field of enquiry, both to the Physiologist, and to the student in Physico-Theology.

In the fossil Flora, we have not only the existing fundamental distinctions between Endogenous and Exogenous plants, but we have also agreement in the details of structure, throughout numerous families, which indicates the influence of the same Laws, that regulate the development of the living members of the vegetable kingdom.

The remains of Fructification, also; found occasionally with the plants of all formations, shew still further, that the principles of vegetable Reproduction have at all times been the same.

The exquisite organizations which are disclosed by the microscope, in that which to the naked eye is but a log of Lignite, or lump of Coal, not only demonstrate the adaptation of means to ends, but the application also of similar means, to effect corresponding ends, throughout the several Creations which have modified the changing forms of vegetable life.

Such combinations of contrivances, varying with the varied conditions of the earth, not only prove the existence of a Designer from the existence of method, and design; but from the Connexion of parts, and Unity of purpose, which pervade the entirety of one vast, and complex, but harmonious Whole, shew that One, and the same mind gave origin and efficacy to them all.

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CHAPTER XIX.

Proofs of Design in the Dispositions of Strata of the Carboniferous Order.

In reviewing the History and geological position of vegetables which have passed into the state of mineral coal, we have seen that our grand supplies of fossil fuel are derived almost exclusively from strata of the Transition series. Examples of Coal in any of the Secondary strata are few and insignificant; whilst the Lignites of the Tertiary formations, although they occasionally present small deposits of compact and useful fuel, exert no important influence on the economical condition of mankind.*

Before we had acquired by experiment some extensive knowledge of the contents of each series of formations which the Geologist can readily identify, there was no a priori reason to expect the presence of coal in any one Series of strata rather than another. Indiscriminate experiments in search of coal, in strata of every formation, were therefore desirable and proper, in an age when even the name of Geology was unknown; but the continuance of such Experiments in districts which are now ascertained to be composed of the non-carboniferous strata of the Secondary and Tertiary Series, can no longer be justified, since the accumulated experience of many years has proved, that it is only in those strata of the Transition series which have been designated as the Carboniferous Order, that productive Coal mines on a large scale have ever been discovered.