CLASSIFICA TIOiV OF FERA^S. 



25 



son ; and, lastly, that it is as yet but a group of 

 individuals placed together for convenience in ar- 

 ranging a systematic classification of the whole. 



Taking an average among authors, we may say 

 that there are 2,500 species of ferns. Hooker's 

 " Synopsis Filicum," in its first edition, gives 2,228 

 species: in the second, by Baker in 1874, there 

 are mentioned 2,646. Linnaeus knew but 190 

 species. 



These species are united, according to various 

 authors, into genera, which number from eleven 

 to two hundred and thirty, as follows : — 



Linnaeus 1 1 



Presl 230 



F^e(i852) 181 



Moore (1857) 178 



Hooker and Baker (1874) .... 76 



J. Smith (1875) • • • • • • 220 



There is much to be said against multiplying 

 species ; but it is certainly fair to admit with Smith 

 that it is easier to remember six or eight genera, 

 each containing fifty species, than to carry in the 

 mind the four hundred and forty-eight species of 

 Polypodium as given by Hooker and Baker in 

 1874. The various genera are constructed upon 

 the different modes of fruiting, and the position of 

 the fruit upon the frond : as, for instance, whether 

 or not there be a covering {jndtismiit) to protect 

 the spore-cases; whether the fruit be at the middle 



