﻿RARE FORMS OF FERNS.-VII. 



A Slender Leaved Cystopteris. 



The brittle bladder fern (Cystopteris fragilis) is dis- 

 tributed practically throughout the world. From 

 Alaska and Iceland to the tropics, from Japan and Si- 

 beria to the Cape of Good Hope, from sea level to alti- 

 tudes of more than three miles above it, on wet or dry 

 rocks and its woods, it finds a home. The varying" 

 habitats to which it has been obliged to adapt itself 

 have not failed to leave their impress upon the plant in 

 the shape of changed form in the fronds and altered 

 stature, yet through all these vicissitudes it has man- 



aged to maintain its characteristic features so nearh 

 unchanged that all the varying forms are still con- 

 sidered as belonging to a single species. The differ- 

 ences exhibited by different plants, however, have not 

 failed to confuse the systematists and in looking up 

 the synonmy of the species, one finds that no less than 

 twenty-five different names have been given to it. In 

 view of these facts, one must be confident, indeed, whc 

 would venture to describe a new form, but the speci- 

 men which is illustrated herewith is so markedly dif- 



Basal Pinna Reduced One-Fourth. 



75 



