My first object will be to show how the fossil remains of the terrestrial animals are connected with the theory of the earth. I shall afterwards explain the principles by which fossil bones may be identified. I shall give a rapid sketch of new species discovered by the application of these principles. I shall then show how far these varieties may extend, owing to the influence of the climate and domestication. I shall then conceive myself justified in concluding that the more considerable differences which I have discovered are the results of very important catastrophes. Afterwards I shall explain the peculiar influence which my researches should exercise on the received opinions concerning the revolutions of the globe. Finally, I shall examine how far the civil and religious history of nations accords with the results of observation on the physical history of the earth. When we traverse those fertile plains, where tranquil waters cherish, as they flow, an abundant vegetation, and where the soil, trod by a numerous people, adorned with flourishing villages, rich cities, and superb monuments, is never disturbed save by the ravages of war, or the oppression of power, we can hardly believe that Nature has also had her internal commotions. But our opinions change when we dig into this apparently peaceful soil, or ascend its neighboring hills. The lowest and most level soils are composed of horizontal strata, and all contain marine productions to an innumerable extent. The hills to a very considerable height are composed of similar strata and similar productions. The shells are sometimes so numerous as to form the entire mass of the soil, and all quarters of the globe exhibit the same phenomenon. The time is past when ignorance could maintain that these remains of organised bodies resulted from the caprice of Nature, and were productions formed in the bosom of the earth by its generative powers; for a scrupulous comparison of the remains shows not the slightest difference between the fossil shells and those that are now found in the ocean. It is clear, then, that they inhabited the sea, and that they were deposited by the sea in the places where they are now found; and it follows, too, that the sea rested in these places long enough to form regular, dense, vast deposits of aquatic animals. The bed of the sea, accordingly, must have undergone some change either in extent or situation. Further, we find under the horizontal strata, _inclined_ strata. Thus the sea, previously to the formation of the horizontal strata, must have formed others, which have been broken, inclined, and overturned by some unknown causes. More than this, we find that the fossils vary with the depth of the strata, and that the fossils of the deeper and more ancient strata exhibit a formation proper to themselves; and we find in some of the strata, too, remains of terrestrial life.