at the Surface of the Terrestrial Globe. 391 



systems taught, and wliicli formerly represented the whole of 

 tliese organized beings as forming a graduated series, rising 

 without interruption from beings the most imperfect to man, 

 who now reigns supreme on the earth; nor yet with that 

 other opinion which, denying all succession, sees nothing in 

 the whole of creation but a variegated assemblage of diverse 

 forms, which is to be traced to one and the same epoch, and 

 has no other connecting bond but that of a common existence. 

 Facts equally contradict these two systems, to which all the 

 others may be referred, and of which they are merely varied 

 commentaries. 



The most prominent result to which paleontological studies 

 have conducted us, consists in the demonstration of a series of 

 epochs independent of one another, in limits more or less ex 

 tended, during which living beings have been different. (By 

 an independent epoch I mean a lapse of time during which 

 organized beings presented the same characters, increasing and 

 multiplying by means of generation, and presenting a spectacle 

 analogous to that which we now see every day at the surface 

 of the globe, where numerous very various species live mixed 

 together, and propagate within determinate limits, without 

 undergoing any notable alteration.) These different epochs 

 ought to be regarded as independent of one another, because 

 the differences presented by the debris of organized beings 

 which characterize them do not correspond, in their na- 

 ture and their intensity, with the modifications which beings 

 now living undergo, in consequence of the influence of time, 

 of climate, and of domesticity. Let us select as an exam- 

 ple, an epoch when no reptiles yet existed. Is there any 

 one familiar with the laws of physiology, who will affirm 

 that the first reptile which lived on the earth descended 

 by means of generation, or in any other manner, from any 

 one of the fishes which existed anteriorly? And, continu- 

 ing the same reasoning with regard to the mammifera and to 

 birds, is it possible to regard them as descending from rep- 

 tiles? Or such and such a family of carnivorous mammifera, 

 of a more recent period, as descending from some more ancient 

 family of herbivora ? Such questions, at the present day, 

 carry with them their own answers; and the objections drawn 



