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We know to-day that unknown extinct animals cannot be 

 restored from a single tooth or claw, unless they are very 

 similar to forms already known. Had Cuvier, himself, applied 

 his methods to many forms from the early Tertiary or older 

 formations, he would have failed. If, for instance, he had had 

 before him the disconnected fragments of an Eocene Tillodont, 

 he would undoubtedly have referred a molar tooth to one of 

 his Pachyderms ; an incisor tooth to a Rodent ; and a claw bone 

 to a Carnivore. The tooth of a Hesperornis would have given 

 him no possible hint of the rest of the skeleton, nor its swim- 

 ming feet the slightest clue to the ostrich-like sternum or skull. 

 And yet, the earnest belief in his own methods led Cuvier 

 to some of his most important discoveries. 



Jean Lamarck (1744-1829), the philosopher and naturalist, 

 a colleague of Cuvier, was a learned botanist before he became 

 a zoologist. His researches on the invertebrate fossils of the 

 Paris Basin, although less striking, were not less important 

 than those of Cuvier on the vertebrates ; while the conclu- 

 sions he derived from them form the basis of modern biology. 

 Lamarck's method of investigation was the same, essentially, as 

 that used by Cuvier, namely : a direct comparison of fossils 

 with living forms. In this way, he soon ascertained that the 

 fossil shells imbedded in the strata beneath Paris were, many 

 of them, extinct species, and those of different strata differed 

 from each other. His first memoir on this subject appeared 

 in 1802,* and, with his later works, effected a revolution in 

 conchology. His " System of Invertebrate Animals" appeared 

 the year before, and his famous "Philosophic Zoologique," in 

 1809. In these two works, Lamarck first announced the princi- 

 ples of Evolution. In the first volume of his " Natural Iiistory 

 of Invertebrate Animals,"f he gave his theory in detail ; and 

 to-day one can only read with astonishment his far-reaching 

 anticipations of modern science. These views were strongly 



* Memoires sur les fossiles des environs de Paris. 1802-6. 



f Histoire natu/relle des animaux sans vertebres. 1 vols. Paris, 18)5-1822. 

 2d edition. 11 vols. 1835-1845. 



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