In examining the records of fossil life, Cuvier and others saw that the evidence indicated a succession of animal populations that had become extinct, and also that myriads of new forms of life appeared in the rocks of succeeding ages. Here Cuvier, who believed that species were fixed and unalterable, was confronted with a puzzling problem. In attempting to account for the extinction of life, and what seemed to him the creation of new forms, he could see no way out consistent with his theoretical views except to assume that the earth had periodically been the scene of great catastrophes, of which the Mosaic deluge was the most recent, but possibly not the last. He supposed that these cataclysms of nature resulted in the extinction of all life, and that after each catastrophe the salubrious condition of the earth was restored, and that it was re-peopled by a new creation of living beings. This conception, known as the theory of catastrophism, was an obstacle to the progress of science. It is to be regretted that Cuvier was not able to accept the views of his illustrious contemporary Lamarck, who believed that the variations in fossil life, as well as those of living forms, were owing to gradual transformations. Lamarck Founds Invertebrate Palæontology.--The credit of founding the science of palæontology does not belong exclusively to Cuvier. Associated with his name as co-founders are those of Lamarck and William Smith. Lamarck, that quiet, forceful thinker who for so many years worked by the side of Cuvier, founded the science of invertebrate palæontology. The large bones with which Cuvier worked were more easy to be recognized as unique or as belonging to extinct animals than the shells which occurred in abundance in the rocks about Paris. The latter were more difficult to place in their true position because the number of forms of life in the sea is very extended and very diverse. Just as Cuvier was a complete master of knowledge regarding vertebrate organization, so Lamarck was equally a master of that vast domain of animal forms which are of a lower grade of organization--the invertebrates. From his study of the collections of shells and other invertebrate forms from the rocks, Lamarck created invertebrate palæontology and this, coupled with the work of Cuvier, formed the foundations of the entire field.