BY HENRY DEANE. 589 



sound in principle, when it consists in comparing fossil remains 

 from successive horizons with existing plants growing in the same 

 or in contiguous regions, but it is quite a different thing when the 

 attempt is made to prove that certain fossil forms belong to 

 groups non-existent in this particular part of the world and found 

 on the other side of the equator, and perhaps in another hemi- 

 sphere. 



