THE MARSH BUCKLER FERN 
341 
Description. — The ironds of this Fern — which grow from 
creeping, blackish rhizomas, furnished with an abundance of 
long fibrous roots — are of two kinds, barren and fertile, the 
former being the longest and reaching a length sometimes 
ot tour teet ; whilst the barren fronds are of lengths varying 
from a foot to three feet or more. Let us take the barren 
irond first. The stem — thin, very slender and brittle — is 
about equal to the leafy part of the frond. It and the 
rachis are pale-green in colour. The form of the leafy 
portion is lance-shaped, broadest in the centre, taper- 
ing to a point at the apex, and tapering somewhat also 
towards the base. The pimne are somewhat distant, irre- 
gularly lance-shaped, pointed at their apices and pinnatifid, 
or deeply cleft into short, oblong blunt-pointed or rounded 
pinnules, connected at their bases by a narrow leafy 
wing running along on both sides of the mid-stems of the 
pinnae. So thin is the texture of this Fern, that the 
venation can be distinctly seen on holding a frond against 
the light. The mid-veins of the pinnules are wavy, and are 
again divided into alternate branched venules. In the 
fertile fronds the pinnules are somewhat more contracted or 
bent under, and the venules bear upon them the almost 
circular clusters of seed-cases, furnished with thin, small, 
and circular indusia, midway between the mid- veins and the 
margins of the pinnules. The indusia are, however, soon 
thrown off by the development of the spore cases, and 
disappear. The seed-clusters then usually become con- 
fluent, or run together, and are partially protected by the 
margins of the pinnules, which are bent back and over 
them. 
Distribution. — Like the majority of our British Ferns, the 
present species is very generally distributed over the con- 
tinent of Europe. It is also an inhabitant of the islands of 
the Atlantic Ocean, of the north-western part of Asia, of 
