in these levels if the animals actually existed in those times.  But the meaning of these facts escaped Cuvier’s mind.  He was a believer in special creation, like Linnaeus and all but a few among his predecessors, and he explained the diversity of the faunas of different geological times in what seems to us a very simple and naive way.  In the beginning, he held, when the world was created, it was furnished with a complete set of animals and plants.  Then some great upheaval of nature occurred which overwhelmed and destroyed all living creatures.  The Creator then, in Cuvier’s view, proceeded to construct a new series of animals and plants, which were not identical with those of the former time, but were created according to the same general working plans or architectural schemes employed before.  Another cataclysm was supposed to have occurred, which destroyed the second series of organisms and laid a new covering of rocks over the earth’s surface for a subsequent period of relative quiet; and so the process was continued.  By this account, Cuvier endeavored to reconcile the doctrine of supernatural creation and intervention with the obvious facts that organisms have differed at various times in the earth’s history.  Although he saw that animals of successive periods displayed similar structures, like the skeleton of vertebrates, which testified to some connection, Cuvier could not bring himself to believe that this connection was a genealogical one.

Mainly through the influence of the renowned English man of science, Charles Lyell, the students of the earth came to the conclusion that its manifold structures had developed by a slow and orderly process that was entirely natural; for they found no evidence of any sudden and drastic world-wide remodeling such as that postulated by the Cuvierian hypothesis of catastrophe.  The battle waged for many years; but now naturalists believe that the forces, of nature, whose workings may be seen on all sides at the present time, have reconstructed the continents and ocean beds in the past in the same way that they work to-day.  The long name of “uniformitarianism” is given to Lyell’s doctrine, which has exerted an influence upon knowledge far outside the department of geology.  Darwin tells us how much he himself was impressed by it, and how it led him to study the factors at work upon organic things to see if he could discern evidence of a biological uniformitarianism, according to which the past history of living things might be interpreted through an understanding of their present lives.

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What, now, are the reasons why the palaeontological evidence is not complete and why it cannot be?  In the first place the seeker after fossil remains finds about three fifths of the earth’s surface under water so that he cannot explore vast areas of the present ocean beds which were formerly dry land and the homes of now extinct animals.  Thus the field of investigation is seriously restricted at