14 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



thus people a land where they were until then un- 

 known. 



" Now let a naturalist, after studying this ani- 

 mated nature, set to work to search the soil on 

 which it lives, and he will discover in it remains of 

 entirely different beings. 



" What, under this supposition, New Holland 

 would be, Europe, Siberia, and a great part of 

 America are in fact ; and perhaps it will be found 

 one day, when other countries, including New 

 Holland itself, are examined, that they have all 

 undergone similar revolutions, I might almost say 

 exchanges of production. For, let us carry the 

 supposition further : subsequent to this transport 

 of Asiatic animals into New Holland, let us admit 

 a second cataclysm, which should destroy Asia, 

 their primitive country, and we should be as much 

 at a loss to discover whence they came as we can 

 be to find the origin of our own animals " (Discours 

 Preliminaire, 1812, p. 81). 



The reader will no doubt kindly excuse the length 

 of this extract, which is of considerable interest. 

 It gives evidence that to Cuvier must be ascribed 

 the honour of having stated with admirable clear- 

 ness and exactness the highly important and fruitful 

 hypothesis of the renewal of faunas by migration. 



Thus the ideas of Cuvier on the transformations 

 of the terrestrial faunas in geological times may 

 be summed up in the following points : (1) succes- 

 sive faunas are entirely or almost entirely different 

 from one another ; (2) their extinction results from 

 sudden revolutions, that is to say, subsidences of 

 the earth's crust, followed by invasions by the sea 



