180 
HISTORY OF BRITISH FERNS. 
The usual forms of this species occur abundantly in 
moist mountainous districts, and also on walls, but gener- 
ally in moist rocky situations throughout the United 
Kingdom, Ireland excepted, where it is comparatively 
rare. The same species is very widely dispersed in various 
parts of the world. The varieties are more rare. Cysto- 
pteris fragilis may be said to have rather a preference to 
^ limestone. Under cultivation it is one of the most 
manageable of the smaller sorts, growing freely on rock- 
work or in pots. Its fronds are produced very early in 
spring, are often renewed during summer, and continue to 
grow up in succession until the frosts cut them off. Being 
so very delicate in texture, the first frosts which have 
access to them do this. 
The names of CyatJiea fragilis^ G. cynapifolia^ C. an- 
thriscifolia, G. dentata ; Gystea fragilis^ G. angustata, 
G. dentata ; Polypodium fragile^ P. cynapifolium^ P. 
anthriscifolium^ P. dentatum^ P. rJiwticum; Aspidium 
fragile^ A. dentatum^ and A. rJiceticum^ have been given 
by various authors to the difierent forms of this variable 
species. 
