280 FROM THE GREEKS TO DARWIN 



up in the following points: (1) successive faunas are 

 entirely or almost entirely different from one an- 

 other ; (2) their extinction results from sudden revo- 

 lutions, that is to say, subsidences of the earth's 

 crust, followed by invasions by the sea of continents 

 once dry; (3) other revolutions resulting in the up- 

 heaval of mountain chains have again cast back the 

 waters and allowed, on the foundation of the dried 

 bottom of the sea, the constitution of continental soils 

 favourable to the expansion of new terrestrial faunas ; 

 (4j) these new faunas are not created on the spot, 

 but come from distant regions, their migration from 

 which has become possible owing to temporary 

 bridges between continents. 



Deperet^ regards as unjustifiable the attribu- 

 tion to Cuvier of successive creations: 



Nowhere in the work of Cuvier is the word [suc- 

 cessive] "creation" to be met with, and we have only 

 to read attentively the Discours sur les Revolutions 

 du Globe to see that in the mind of the illustrious 

 scholar it was simply a question of the invasions of 

 new animal forms suddenly arriving from distant and 

 unknown countries. Here the idea is fundamental 

 enough to warrant its quotation : "Moreover, when I 

 maintain," says Cuvier, "that the beds of rock con- 

 tain the bones of several genera and the friable strata 

 those of several species which no longer exist, / do 

 not assume that a new creation was n&cessary to pro- 

 duce the existing species. I simply say that they did 



'^Loc. cit.i pp. lS-14. 



