AGE OF THE LIGNITIG DETERMINED liV ITH I'l.ORA. 313 



lo the geological distribution of tlie plants, I have marked upon llie pages 

 of ex])lanations, and after the name of each species, numbers indicating the 

 geological divisions which they repres(uit, while the table of distribution 

 shows the localities from which the plants are derived and the groups to 

 which they arc referred. 



This table of distribution will be easily understood. The references 

 to species of geological groups, either European or American, are not equally 

 precise. They are marked by the note of interrogation (?), or by the excla- 

 mation point (!), according to the degree of relation or of identity, both 

 being either positive or more or less indefinite. 



