3O Introduction. 



site is the received geological theory, namely, that every 

 stratum contains its own special fauna and flora, and 

 when those of one epoch are found intermixed with the 

 fauna and flora of another epoch or stratum, that, in such 

 case, they are derived impurities, and the organic remains 

 are NOT in the place they were first deposited as sedi- 

 mentary rocks. 



