THE SURFACE OF THE GLOBE. Oy 



then taken up by recent alluvial deposites : and recent bones may have 

 fallen into the clefts and caverns of the ancient rocks, and then have 

 been enveloped by stalactites or other incrustations. It would be ne- 

 cessary, in every case, to analyse and justly determine on all these 

 circumstances which might veil from the sight the real origin of fossils ; 

 and persons who have collected bones have very seldom doubted of 

 this necessity; whence it follows, that the real nature of their geolo- 

 gical position have nearly always been neglected or misunderstood. 



Thirdly, there are some doubtful species, which would more or less 

 alter the certainty of these results, just as long as clear distinctions 

 with regard to them were not made out ; thus horses and buffaloes, 

 which are found with elephants, have not yet peculiar and specific 

 characters ; and geologists, who will not adopt my different epochs for 

 fossil bones, will still be able to draw from them, for many years, an 

 argument useful and convenient, as it is from my book that they will 

 derive it. 



But although it may be said that these epochs are capable of some 

 objections with persons who but slightly consider some particular case, 

 I am no less persuaded that those who will adopt the whole of these 

 phenomena will not be checked by these small and partial difficulties, 

 and will acknowledge with me, that there has been one and probably 

 two successions in the class of quadrupeds before that which now peo- 

 ples the surface of our continents. 



I here expect another objection; one has been made already. 



The Extinct Species are not varieties of Living Species. 



Why, I am asked, should not the present race be modifications of 

 those ancient races which we find among fossils, modifications which 

 would have been produced by local circumstances and change of 

 climate, and brought to this great difference by a long series of 

 years ? 



This objection must appear very cogent with those who believe in 

 the undefined possibility of the change of forms in organized bodies, 

 . and who think that with ages and habits every species may change, 

 one into another, or result from a single one amongst them. 



We may answer them in their own way ; that, if the species has 

 gradually changed, we must find traces of these gradual modifications ; 

 that between the paleeotheria and the present species we should have 

 discovered some intermediate formation ; but to the present time none 

 of these have appeared. 



Why have not the bowels of the earth preserved the monuments of 

 so remarkable a genealogy, unless it be that the species of former ages 



