CYSTOPTERIS FRAGILIS. 119 
crowded, and finally running together ; at first pale, but 
becoming black, and covering the whole back of each 
leafit. The cover (indusium) of the masses of spores is 
white, loose, membranous, sinking inward, irregularly 
jagged, sometimes lengthened to a point, but soon 
turned back, and forced off by the spores, which are 
black when young, but become browner with age. 
This species is extremely liable to alter its form ac- 
cording to the temperature of the season, and the moist- 
ness or dryuess of the situation ; but such alterations 
are not in any way permanent. 
It is not an uncommon Fern in mountain districts, 
especially on old walls, and chalky, damp, shaded rocks. 
In England it has been found at Richmond, and 
Settle, in Yorkshire; Peveril Castle, Peak's Hole, 
Castleton, Lovers Leap, near Buxton, and Matlock, in 
Derbyshire ; near Hyde, in Gloucestershire ; Cheddar, 
in Somersetshire; in Nottinghamshire; near Bristol; 
on the ground from Bourn Heath to Wormsash, near 
Bromsgrove ; and at Exwick, near Exeter. 
In Wales, in a cave at Clogwyn Coch, Suowdon, rocks 
above Cwnn Idwel, near Twll Der, and near Wrexham. 
In Scotland, in Aberdeenshire, Moray, Ross-shire, 
near Haens, in Berwickshire; Sutherland and the Kin- 
cardinshire coast ; and near Killin. 
In Ireland, in Kerry, at Lough Inn, and Lough 
Derryclare, Connamarn. 
The first time this Fern is mentioned as a native of 
Britain, we think, was in 1696, by Ray, in the second 
edition of his " Synopsis Methodica Sterpium Britan- 
