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the venules lying parallel, and extending in straight lines
towards the margins, terminating in the barren fronds in
the serratures of the margin, but in the fertile fronds
extending into the indusium, there forming the receptacles
to which the spore-cases are attached. The sori are oblong,
covered by indusia of the same form, each consisting of the
apex of one of the lobes of the frond, changed to a membranous
texture, and folded under. The sori are, as abeady
mentioned, seated on this membranous reflexed lobe, and
by tliis circnmstance the genus may at once be detected by
those who are not conversant with its easily recognized
prim dfac ie appearances.
The Maiden-hair is a local plant, though it has a wide
geographical range. It is found here and there in the
warmer parts of Great Britain and Ireland, evidently preferring
cavernous and rocky situations within the influence
of the sea. What is believed to he the same species is
found in the warmer parts of Europe, in Asia, in the north
of Africa, and in the Canaries and Cape de Verd Islands.
It is, moreover, a tender plant, and does not thrive under
cultivation in the climate even of the south of England,
unless sheltered in a frame or green-house, or by being
covered with a glass. In a Wardian case it grows well;
and attains great luxuriance in a damp hot-house. The
proper soil for it is very light turfy peat, mixed with a considerable
proportion of silver sand, and it is beneficial to
plant it on or around a small lump of free sandstone.
Genus II. ALLOSORUS, Bernhardi.
O f this family we have but one British species, the Allosorus
crispus. It is known from all its fellow-country-ferns
by the coincidence of the following features. It bears fronds
of two kinds, one being leafy and barren, or without sori,
the other contracted, and bearing sori, and hence called
fertile. The edges of the lobes of the fertile fronds are
rolled under (which is what gives them the contracted appearance),
and covers the sori in the stead of a special indusium
; the sori when young form distinct circular clusters
beneath this recurved margin, but as they grow they join
laterally (in technical language, they become confluent),
forming two lines of fructification lengthwise the segments
of the fronds.
The name Allosorus is compounded from the Greek, and
comes from alios, which means various, and sorus, which