a reason for their rise or decline, or why their term of being should have been included rather in one certain period of time than another. The same faculty which finds employment in tracing to their causes the rise and fall of nations, and which it is the merit of the philosophic historian judiciously to exercise, will to a certainty seek employment in this department of history also; and that there will be an appetency for such speculations in the public mind, we may infer from the success, as a literary undertaking, of the “Vestiges of Creation,”—a work that bears the same sort of relation, in this special field to sober inquiry, founded on the true conditions of things, that the legends of the old chroniclers bore to authentic history. The progressive state of geologic science has hitherto militated against the formation of theory of the soberer character. Its facts—still merely in the forming—are necessarily imperfect in their classification, and limited in their amount; and thus the essential data continues incomplete. Besides, the men best acquainted with the basis of fact which already exists, have quite enough to engage them in adding to it. But there are limits to the field of palæontological discovery, in its relation to what may be termed the chronology of organized existence, which, judging from the progress of the science in the past, may be well nigh reached in favored localities, such as the British islands, in about a quarter of a century from the present time; and then, I doubt not, geological history, in legitimate conformity with the laws of mind, and from the existence of the pregnant principle peculiar, according to Cuvier, to that science of which Geology is simply an extension, will assume a very extraordinary form. We cannot yet aspire “to the height of this great argument:” our foundations are in parts still unconsolidated and incomplete, and unfitted to sustain the perfect superstructure which shall one day assuredly rise upon them; but from the little which we can now see, “as if in a glass darkly,” enough appears from which to “Assert eternal Providence, And justify the ways of God to men.”