182 
HISTORY OF BRITISH FERNS. 
the effects of damp in winter, has been found on an old 
wall at Leyton, in Essex. Its claim to aboriginality is 
strongly suspected, a small, much-divided form of Cysto- 
pteris fragilis being supposed to have been mistaken for 
it. The Scotch and Welsh plants which have been called 
Cystopteris alpina are probably open to this objection, but 
the Essex plant is no doubt genuine ; and fronds of the 
true plant have been communicated by Mr. Shepherd of 
Liverpool, as having been gathered in Derbyshire and 
Yorkshire ; and we have seen others from the Lake district. 
It occurs in the alpine parts of southern Europe. 
Cystopteris alpina is another name for this elegant plant, 
which has also been called Cyathea regia and Cyathea 
incisa, Cystea regia, Polypodium regium, Polypodium 
alpinum, Aspidium regium, and Polypodium trifidum, 
Cystopteris montana, Linh 
The Mountain Bladder-Fern, (Plate XIV. fig. 2.) 
This is one of the rarest of our native Ferns, and hence 
is a plant of great interest. It is a small species, growing 
with a slender creeping 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 
