870 CHARACTERS OF TRIBES AND GENERA. 



zones. B. ternatum and JB. Virginica have also a wide 

 geographical range, being found very generally throughout 

 the temperate and tropical zones ; the influence of the 

 various climates causing much variation in the more or 

 less divisions of the fronds, many of the states having 

 been described as distinct species. 



Presl describes no less than seventeen species, which 

 in the " Synopsis Filicum " are reduced to six. 



Total number of species quoted, 1815. 



