THEORY OF THE EARTH. 101 



bones themselves. The same formation may ap- 

 pear recent in places where it shews itself at the 

 surface, and ancient in those where it is covered 

 by the beds which have succeeded it. Ancient 

 formations may have been transported by partial 

 inundations, and thus have covered recent bones ; 

 they may have fallen upon them by crumbling, 

 and thus have enveloped and mingled them with 

 the productions of the ancient sea, which they 

 previously contained. Bones of ancient periods 

 may have been washed out by the waters, and 

 afterwards enveloped in recent alluvial formations. 

 Lastly, recent bones may have fallen into the 

 fissures or caverns of ancient rocks, and been en- 

 veloped by stalactites or other incrustations. In 

 every individual instance, therefore, it becomes 

 necessary to analyze and appreciate all those cir- 

 cumstances which might disguise the real origin 

 of fossil remains; and it rarely happens that people 

 who have collected bones have been themselves 

 aware of this necessity, the consequence of which 

 has been, that the true characters of their geolo- 

 gical position have been almost always neglected 

 or misunderstood. 



Thirdly, there are some doubtful species, which 

 must occasion more or less uncertainty in the re- 

 sults of our researches, until they have been clearly 

 ascertained. Thus the horses and buffaloes that 

 occur along with the elephants, have not yet re- 



