98 
HISTORY OF BRITISH FERNS. 
barren, but this is on account of their margin being revo- 
lutely bent under. The venation of the lobes of this Pern 
consists of a distinct, somewhat wavy midvein, from which 
alternate venules branch out, these being usually forked, 
and both branches bearing a sorus half-way between the 
margin and the midvein. The sori, which are numerous 
and closely placed, often become confluent, and are par- 
tially concealed by the bent-back margin. The indusium, 
or cover of the spore-cases, is in this species small, thin, 
and shapeless, and is soon thrown off and lost. 
The Marsh Buckler Fern has a wide geographical range, 
and in England and Wales occurs in numerous localities ; 
in Scotland and Ireland it is rather uncommon. 
It is not a very attractive species for cultivation, but 
grows freely if planted in a moist peaty situation, where 
its rambling stems have room to spread. It has been 
severally referred, under the individual name of Thelypteris^ 
to the families of Aspidium, Polypodium, Acrostichum, 
and Polystichum, by various botanical writers. The names 
of Thelypteris palustris Hemestheum Thelypteris 
also been given to it. 
