152 LAMARCK, HIS LIFE AND WORK 



in organized bodies, and think that during a succes- 

 sion of ages, and by alternations of habits, all the 

 species may change into each other, or one of them 

 give birth to ail the rest. Yet to these persons the 

 following answer may be given from their own sys- 

 tem : If the species have changed by degrees, as they 

 assume, we ought to find traces of this gradual modi- 

 fication. Thus, between the Palseotherium and the 

 species of our own days, we should be able to dis- 

 cover some intermediate forms ; and yet no such 

 discovery has ever been made. Since the bowels of 

 the earth have not preserved monuments of this 

 strange genealogy, we have a right to conclude that 

 the ancient and now extinct species were as perma- 

 nent in their forms and characters as those which exist 

 at present ; or, at least, that the catastrophe which 

 destroyed them did not have sufficient time for the 

 production of the changes that are alleged to have 

 taken place." 



Cuvier thus emphatically rejects all idea that any 

 of the tertiary mammals could have been the ancestral 

 forms of those now existing. 



" From all these well-established facts, there does 

 not seem to be the smallest foundation for supposing 

 that the new genera which I have discovered or es- 

 tablished among extraneous fossils, such as the palceo- 

 therium, anaplotherium, megalonynx, mastodon, ptero- 

 dactylis, etc., have ever been the sources of any of 

 our present animals, which only differ as far as they 

 are influenced by time or climate. Even if it should 

 prove true, which I am far from believing to be the 

 case, that the fossil elephants, rhinoceroses, elks, and 

 bears do not differ further from the present existing 

 species of the same genera than the present races of 

 dogs differ among themselves, this would by no 

 means be a sufficient reason to conclude that they 



