THE THEORY OF SUCCESSIVE CREATIONS 19 



mystery which envelops it " (Cours elementaire, 

 t. II., p. 251). 



Thus two points are, in d'Orbigny's mind, abso- 

 lutely certain : on the one hand, the creation of 

 complete faunas at one swoop an opinion never 

 formulated by Cuvier ; on the other hand, the 

 sudden disappearance of each of these faunas. As 

 regards the first of these great facts, the learned 

 paleontologist does not, as we have seen above, 

 attempt the slightest scientific explanation. As 

 to the disappearance of faunas, he, on the other 

 hand, discusses the probable causes, and puts aside 

 as wholly insufficient the biological or climatological 

 changes at various epochs in the existence of the 

 earth. There only remains, as an explanation of 

 the annihilation of all the beings which have twenty- 

 seven times succeeded one another on the globe, the 

 effects of geological disturbances, or powerful dis- 

 locations of the earth's crust bringing about a 

 great displacement of the seas, which must have 

 reacted at once on both terrestrial and marine 

 animals. This, as will be seen, is an almost integral 

 reproduction of the Revolutions du Globe of Cuvier 

 with a still wider generalization. 



My readers will no doubt ask themselves what 

 powerful motives, drawn from observed facts, can 

 have brought about so clear and so deep a convic- 

 tion in the mind of an eminent naturalist like 

 Alcide d'Orbigny, who was also a sagacious and 

 strict observer of the relations and differences be- 

 tween fossil species, and an indefatigable traveller 

 who had studied on the spot the conditions of the 

 fossil deposits of most countries in Europe, and 



