"In truth these displacements, which are never interrupted, are in general only made with extreme and almost inappreciable slowness, but they are in ceaseless operation, and with such constancy that the ocean bottom, which necessarily loses on one side while it gains on another, has already, without doubt, spread over not only once, but even several times, every point of the surface of the globe. "If it is thus, if each point of the surface of the terrestrial globe has been in turn dominated by the seas--that is to say, has contributed to form the bed of those immense masses of water which constitute the ocean--it should result (1) that the insensible but uninterrupted transfer of the bed of the ocean over the whole surface of the globe has given place to deposits of the remains of marine animals which we should find in a fossil state; (2) that this translation of the ocean basin should be the reason why the dry portions of the earth are always more elevated than the level of the sea; so that the old ocean bed should become exposed without being elevated above the sea, and without consequently giving rise to the formation of mountains which we observe in so many different regions of the naked parts of our globe." Thus littoral shells of many genera, such as Pectens, Tellinæ, cockle shells, turban shells (_sabots_), etc., madrepores and other littoral polyps, the bones of marine or of amphibious animals which have lived near the sea, and which occur as fossils, are then unimpeachable monuments of the sojourn of the sea on the points of the dry parts of the globe where we observe their deposits, and besides these occur deep-water forms. "Thus the encrinites, the belemnites, the orthoceratites, the ostracites, the terebratules, etc., all animals which habitually live at the bottom, found for the most part among the fossils deposited on the point of the globe in question, are unimpeachable witnesses which attest that this same place was once part of the bottom or great depths of the sea." He then attempts to prove, and does so satisfactorily, that the shells he refers to are what he calls deep-water (pélagiennes). He proves the truth of his thesis by the following facts: