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separate them, those of lanceolatum being lance-shaped, or
tapering from near the middle towards the base, while those
of Adiantum-nigrum are always triangular, or broadest at
the base. The pinnæ spread at nearly right angles with the
rachis, often, but not always, opposite, and have an ovate-
lanceolate form ; they are again pinnate, so that the frond
is bipinnate. The pinnules are of irregular form, often
obovate, or nearly so, sometimes unequally quadrate, but
always indented on the margin with deep, sharp teeth, the
larger pinnules being first lobed, and the lobes toothed,
the smaller ones simply toothed.
The venation is tolerably distinct; the pinnules each
having a tortuous midvein, which produces forked venules,
one of the veinlets of which extends towards each serrature.
The sori have no very definite order; they are at first oblong,
and covered by an indusium of the same form, having
a lacerated free margin; but as they become old the sides
become bulged out so as to give them a roundish form, and
the indusium becomes obliterated.
This is rather a local species, being found only in the
southern and western parts of England, and in Wales, almost
always near the coast. It is found very luxuriant in the
Channel Islands.
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