64 FEENS OP aHEAT BRITAIN. 



well known to the cultivator of Fams, retaining its pecu- 

 liarities in the greenhouse or closed case. Its height 

 varies from about four to six inches. The Gystopteris 

 dentita, besides being often described as a variety of 

 C. frdgilis, is also caUed by different botanists CyatJiea 

 dentdta, or Cystea dentdta. 



3. Cpsfqpteri$ montdna (Mountain Bladder-feirn, or 

 Wilson's Earn). — Fronds triangular, thrice pinnate j pin- 

 ntdes of lower pinnae pinnate; lobes pinnatifid, with 

 linear notched isegments. This fern, which is of very 

 elegant form, is the rarest of all our British species. 

 It is very distinct from the preceding, and its small 

 triangular very compound fronds are from four to six 

 inches high. It has a slender creeping scaly under- 

 ground stem, with dark wiry roots. The stalk is about 

 twice as long as the leafy portion of the frond, the pinnse 

 are opposite to each other, and the lower pair are much 

 longer than the others ; these gradually diminish in size 

 towards the upper part of the frond. This plant is 

 exceedingly frail and delicate, almost transparent in tex- 

 ture, and it is one of the most compound of our British 

 Ferns. The lower part of the frond is thrice, and the 

 upper part twice pinnate, and it has the peculiarity of 

 having the lower side of the lower pinnse broader than 

 the uppermost side, and some of the upper branches 

 sometimes exhibit this inequality. The lower pinnae are 

 divided on the lower side into pinnules, which are egg- 

 shaped or lanceolate in form, and these are again divided 

 into pinnules, which are egg-shaped or oblong and 

 notched, the pinnules on the upper side being of the 

 same form as the secondary pinmdes of the lower side. 



