274 Professor Pictet on the Succession of Animals. 



them ; but I must premise that, although one of them is less 

 directly open to attack than the rest, none appear to me in 

 all respects satisfactory ; and I believe that even the theory 

 which may be considered as the best, does not perhaps ex- 

 plain all the facts. In the hope, then, that time and the 

 progress of palaeontology will one day furnish a better solu- 

 tion, I shall confine myself to an exposition of the present 

 state of the science. 



The explanations which have been given of the succession 

 of these different faunas on the surface of the globe may be 

 reduced to three. 



The first sets out with the fact that the cataclysms which 

 have buried the various species found in a fossil state, have 

 been partial ; and it supposes that after each inundation 

 which has entombed the beings of one epoch, the formations, 

 having again dried up, have been repeopled by the animals 

 of the neighbouring countries, which differed from the former 

 in the same manner as the faunas of the different regions of 

 the globe are now found to differ. A succession of similar 

 occurrences in the same country would, according to this 

 notion, leave its traces in the different superimposed for- 

 mations. The same thing would take place, in an inverse 

 sense, in regard to the inhabitants of the seas. 



This idea might have been entitled to discussion, when a 

 very small number of known facts appeared not to be incon- 

 sistent with an explanation which, at first sight, seems simple 

 and natural ; but now that the different formations have 

 been more carefully studied, and in a greater number of 

 countries, the facts no longer accord with this theory, and it 

 may now be afiirmed to be altogether inadmissible. If, in 

 fact, all these superincumbent deposits had been nothing 

 more than the result of a displacement of contemporary 

 faunas, we ought to find the same species buried at different 

 epochs in different countries, and the remains of existing 

 species ought to be preserved as fossils in some formations 

 of neighbouring countries. But all the most trust-worthy 

 investigations prove directly the contrary ; we now possess 

 numerous fossils from Asia and America, and the laws of 

 distribution there are altogether similar to our own ; we do 



