CYSTOPTERIS. 109 



The varieties are more rare, and we know of only one locality, 

 a sea-cave, near Aberdeen, in which Dickieana has been 

 found. Cystopteris 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 frost cuts them off. Being 

 so very delicate in texture, the first frosts which have access 

 to them do this. 



The names of Cyathea fragilis, C. cynapifolia, C.anthris- 

 cifolia, C. dentata ; Cystea fragilis, C. angustata, C. dentata ; 

 Poly podium fragile, P. cynapifolium, P. antJiriscifolium, P. 

 dentatum, P. rh&ticum ; Aspidium fragile, A. dentatum, and 

 A, rhaticum have been given by various authors to the dif- 

 ferent forms of this variable species. 



CYSTOPTERIS MONTANA, Link. The Mountain Bladder- 

 Fern. (Plate XIV, fig. 2.) 



This is the rarest of our native Ferns, and hence is a 

 plant of great interest. It is a small species, growing with 

 a slender creeping scaly stem, by the division of which it is 

 increased. The fronds, which grow up from this caudex, are 

 from four to six or eight inches high, triangular in outline, 



