) THE BRITISH FERNS.
§ V.—L om a rte /E o r B l e c h n e jb .—Sori linear, tra'asherse to the veins, i. e.
ranged longitiidinallij between the midrib and margvns, covered by
special linear indusia.
10. Bleclinum.—Sori forming a continuous lino on each side of,
and parallel witli the midrib, and within the margin.
§ v i.—P t e r i d e j e .—Sori linear, continuous, transverse to the veins, covered by
the reflcxcd 'margin o f the frond, which is altered in texture,
becoming indusiate.
11. Pteris,—Soi'i forming a continuous marginal line, covered by
the indusium-like reflexed edge of tbe segments of tbe
frond.
§ v ii.—A d i a n t e í b .—Sori oblong, rarely elongated, home on the veins o f the xmder
surface o f the transverse indusia, and laterally confiuent; indusium
formed o f the reflexed margin o f the frond, altered in texture.
12. Adiantum,—Sori transverse, growing on tbe reflexed indusium
lilie apices of tbe lobes; lience resupinate.
§ viii. — C y s to p te r id em . — Sori punctiform, covered while young by cucullate
indusia, affixed posteriorly, and inflected hood-like over them.
13. Cystopteris.—Sori covered by ovate cucullate or booded
indusia, wbicb are attached by tbeir broad base.
§ i^:.— P e r a n em e íb o r AVoodsiejs.— Sori punctiform, irwoluerate, i. e. with
the scale-like membrane fixed beneath the sorus.
14. Woodsia.—Sori within involucres whose margin is divided
into incurved capillary segments.
16. HymenophyUum.—Receptacles included within two-valvod
involucres of the same texture as the frond.
•• SPORECASES TWO-VALVED.
T r ib e III.— Osmundinese.— Fructification marginal paniculate; spore-
cases two-valved, opening at top ; ring rudimentary near the apex,
consisting of a few parallel sirice.
17. Osmunda.—Fructification forming irregular, densely-branched
panicles on contracted rachiform segments, at the apex of
the fronds.
N a t u r a l O r d e r OPHIOGLOSSACEÆ, o r A d d e r ’s T o n g u e
F e r n s .
The Ferns belonging to this Order have their fronds plicate or
simply folded in vernation ; their fructification being paniculate or
spioate ; and their two-valved spore-oases without au elastic ring.
• FRUCTIFICATION PANICULATE.
18. Botrychium.—Spore-cases arranged in irregularly-branched
panicles terminating a separate rachiform branch of frond.
** FRUCTIFICATION SPIOATE.
19. Ophioglossum. — Spore-cases forming two-ranked simple
spikes terminating a separate raohifonn branch of frond.
Teibe II.—^Triehomaninese.'—Fructifications extrorse-marginal; spore-
cases without valves bursting irregularly, clustered on veins (receptacles)
which project from the frond, and are surrounded by urnshaped
or two-valved involucres; ring horizontal or oblique, complete,
15. Trichomanes.-—Receptacles exserted, sporangiferous at the
base, where they are surrounded by urn-shaped involucres
of the same texture as the frond.
T. 2