







58 THE BRITISH FERNS. 
pinnatifid, usually more or less drooping. Lobes or segments linear- 
oblong, parallel, flat, blunt bluntish or abruptly acute, obscurely 
serrate, more distant and sometimes deflexed rarely shorter at the 
base, shorter and more crowded or becoming confluent near the apex, 
which sometimes terminates abruptly, but is usually caudate. 
Venation in each lobe consisting of a prominent tortuous midvein 
or costa, which is alternately branched; the branches (veins) are 
again branched, producing from three to five alternate branchlets 
(venules). Of these venules, the lowest anterior one of each fascicle 
(rarely more) bears a sorus at its club-shaped apex, the others being 
sterile, and each terminating within the margin in a small trans- 
parent club-shaped head. 
Fructification on the back of the frond, usually confined to its 
upper part, the sorus originating at the apex of the veinlet ; at first 
a naked depressed scarcely visible spot, and from the earliest period 
at which it becomes visible quite destitute of any apparent mem- 
branous cover, or indusium. Sori or clusters of spore-cases circular, 
rarely somewhat oblong, quite exposed, arranged in a linear series 
on each side the midvein ; at first distinct, often crowded and finally 
confluent. Spore-cases yellow or orange of various shades, becoming 
tawny, numerous, globose, with a slender stalk of elongated cells. 
Spores yellow, muriculate or corrugate, oblong or kidney-shaped. 
Duration. .The rhizome is perennial. The fronds are produced 
about the end of May, and are persistent through the winter and 
until after new fronds are produced, so that the plant is evergreen 
unless the fronds are destroyed or damaged by severe frost. Other 
fronds are produced later in the summer. 
This common plant is the type of the Linnean genus Poly- 
podium ; and as there is no reason, other than the fancy of name- 
makers, why that genus should be abolished, though there may be 
reasons for its reduction by divesting it of ill-assorted species, we 
cannot concur with those who give to this plant the name Cteno- ` 
pteris, used for sectional distinction by Blume and Presl, and who thus 
altogether ignore the Polypodium of Linnseus. Whatever additional 
names the introduction of modern systems of classification may 
render necessary, it is clearly not permissible that the names of 

