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Marattiacea.
TAB. VII.
D A N Æ A . Sm.
Sori dorsales, totam fere paginam pinnarum tegentes, nervis parallelis insidentes.
Indusium coriaceum, oblongum, transversum, raultiloculare ; loculis biseriali-
bus, sporangiferis, poro dehiscentibus : sporangiis oblique ovatis, exannulatis,
ore contracto. Sporuloe minutissimoe, globosoe, muriculatæ.— Filices tropicæ
ex America meridionali. Caudex longus, repens. Frondes simplices v. pinnatæ
subcarnoso-coriaceoe, siccitate fra g ile s et nigricantes. Rachis soepius nodosa, nunc
alata. Pin næ fertiles sierilibiis minores. Venæ pinnatæ ! venulæ parallelte
transversales, simplices vel furcatæ.
D anæ a alata. Sm. ( T a b . \ l l . ) — Hook. et Grev. le. Fil. t. 18.
The real structure of the fructification of this genus is dilficult to he understood. It
would appear from Mr Bauer’s admirahle analysis, that, heneath tlie epidermis, upon each
transverse nerve of the fertile pinnæ, a sorus is formed, surrounded hy a peculiar covering
which I here consider the indusinm, eventually opening with a double line of pores, each
pore communicating with a number of transverse chambers or cells, and each clmmber
having 2 (for there does not appear to be a dissepiment between them) sporangia, obliquely
oval, tliat is flat on their inner side, convex on their outer, fixed to the nerve by a point
at the inner base, contracted and a little prolonged at the mouth, which opens at the pore
of the indusium. These indusia are so crowded as to occupy the whole under side of the
pinnæ, but not reaching to the costa in the middle, nor to the edge on the margin, where
there is constantly a wing-like border.
Fig. 1. Portion of the under side of the fertile frond; magn. 8. diam.—/i 2. A small portion of the
same ; m. 15 diam—f . 3. The upper side of the same ; do.—f . 4. Single sorus ; m. 25 diam - f 5.
Longitudinal section of an indusium ; do.—f . 6. Transverse section of f . 2. shewing the sporangia in
the cells, with their sporules ; do.—f . 7. Sporules ; m. 400 diam.
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