VI PREFA CE. 



In the systematic part the sequence has also been modified, 

 bringing the simpler eusporangiate forms first and introduc- 

 ing the desirable distinction between orders and families 

 which botanists have too long confused. 



The number of species is considerably increased, owing, in 

 part to new discoveries and in part to the seeming necessity 

 of reestablishing the earlier and in many cases clearer views 

 of the earlier writers on ferns, many of whose species have 

 been "reduced to synonymy by the English (Kew) school of 

 fern writers whose dictum has hitherto been followed by 

 American fern students. The number of genera has also 

 been increased in accordance with the views of earlier and 

 more scientific fern students. 



COLUMBIA UNIVERSITY, June, 1900. 



