418 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
paths along which have developed the ideas relative to the appari- 
tion of the “hes which have inhabited the earth during its various 
epochs. 
I. CUVIER AND D’ORBIGNY. 
At the beginning of the nineteenth century, the earlier works of 
Bernard Palissy, Faujas de St. Fonds, Guettard, Buffon, and espe- 
cially Wilham Smith, had made possible a comprehension of the im- 
portance of fossils, by means of which the age of the sedimentary 
deposits of our globe could be determined. 
The researches of Cuvier on fossil faunas led this talented natural- 
ist to announce that there existed in the terrestrial strata a series of 
superimposed and distinct faunas, which had disappeared successively 
and entirely under the influence of violent geological catastrophes, 
which he called the “ revolutions of the globe.” New and different 
faunas replaced the ancient faunas, not through new creations, as was 
commonly said, but by means of faunas derived from regions where 
similar revolutions had not taken place. 
The revolutions of the globe, in the sense in which Cuvier under- 
stood them, were not universal. They resulted from considerable 
changes and extensive modifications in the distribution of seas and 
continents, brought about by the formation of new marine lands or 
the submersion of mountain chains, modifications caused by the cool- 
ing of the earth. 
The two great treatises which summarize the work of Cuvier, one 
the “ Recherches sur les Ossements Fossiles,” and the other, “ Dis- 
cours sur les Révolutions du Globe,” although more than a century 
old, remain as models of clearness of description and of scientific 
interpretation. 
The first is the indispensable remembrancer of all naturalists who 
occupy themselves with the study of living and extinct vertebrate 
faunas; the second, of all geologists or geographers, who find in it 
at least the germs of the explanation of the causes of the physical 
changes wrought in our planet, andeof the laws which govern them. 
Cuvier was, therefore, in reality the creator of paleontology. He first 
showed, contrary to the opinion of Buffon, that fossil animals are dif- 
ferent from living ones, and, prompted by the researches of other 
naturalists, such as A. d’Orbigny, Al. Brongniart, von Buch, W. 
Smith, Werner, ete., who occupied themselves more especially with 
invertebrate animals, asserted that each stage presented peculiar and 
distinct fossils. 
He thereby not only created paleontology, that is, the study of 
the fossils themselves, but also that of the order of ae appearance 
on the globe. Thus, he not only enlarged the boundaries of this new 
science, which is indispensable to zoology, but he made it serve the 
