84 HISTORY OF BRITISH PERNS. 



the sori on their anterior side. The sori are oblong, covered 

 at first by membranous indusia, which are soon pushed aside ; 

 the free margin is jagged or crenate. 



A native of moist,, rocky, mountainous districts in Eng- 

 land, Scotland, and Wales ; occurring, also, though less 

 frequently, in Ireland, and throughout Europe. 



It is not difficult to cultivate in pots in a close, damp, 

 cold frame ; or on moist, shady rock-work, if covered over 

 by a bell-glass. If exposed, it is apt to suffer from occasional 

 excessive wet, which often does not properly drain away ; and 

 also from the dry hot air of our summers. The object of 

 covering it with a glass is to avoid both these casualties, and 

 provided it is not kept too close it will then thrive well. 

 The proper bell-glasses for these half-hardy Perns are those 

 with a small opening in the crown, which may be closed or 

 not at pleasure, but, in general, are best left open. In pots 

 it should have a gritty, porous soil. 



Genus VII. ATHYEIUM, Both. 



IN the Athyrium we have perhaps the most variable of all 

 our native Perns; though the varieties it presents, and 



