species both foliose and frondose hidden in twos and threes, in
small cavities of the epidermis arranged on both sides of the
stem; or in others contained in open monandrous cavities supplied
with a minute incurved bract. Perianth incompletely tubular
(perfectly so in Pallavicinia only); in many species, however,
none is present. Calyptra not often small, generally long and
fleshy, free from the involucre and perianth, hut often more or
less deeply concrete with the receptacle. Sterile pistillidia either
more or less deeply adnate to the calyptra (sometimes only at the
apex), or always arranged along the stem, naked. Capsule in
typical plants subglobose, formed of 2-5 series of cells, dehiscing
more or less irregularly.
B. Elaters monospiral, very acute at each en d ; but a few
short apical ones persisting longer.
Subtribe V III. METZGERIEdE.
Plants frondose, dichotomous or pinnately branched, the
lacinise linear; branches in the genus Aneura all lateral, the
nerve broad laxly cellulose, radiculose beneath, lamina none or
very narrow, rarely of moderate breadth; in the other genus>
Metgyeria, branches extremely seldom lateral and pinnate, all
the floriferous ones (sometimes even those that do not hear
flowers) postical, radicles springing from the nerve and the
margin, now and then from the whole surface. Reproductive
organs of both sexes distichous on the nerve of a shortened
branch; pistillidia 2-20 pairs, styleless; antheridia very frequently
more numerous, very rarely tetrastichous. Perianth
none. Calyptra large, obovate, fleshy, in Aneura very often
papillose, in Metzgeria hairy with radicles. Capsule elongate,
quadrivalvate to the base, of two series of cells. Apical elaters
fixed and interwoven with others that are free, stretched out in
four pencils above the open capsules.
Suborder I I. MARCHANTIACEAl,
Fronds more or less fleshy, prostrate, broadly and indistinctly
nerved, venoso-areolate on the upper surface, areolse as a rule
with one pore, with a cavernous stratum below the pores;
dichotomous, sometimes putting out postical frondules, villous
beneath with very long radicles. Very long hair-like fasciculated
water-carrying ductules fill up the canal beneath the nerve, which
afterwards ascend into the capitulum through the little canals
in the peduncles. Inflorescence in almost all species dioicous,
aorogenous, or epigenous. Andrcecia either peltate and stipitate
or discoid and half immersed; antheridia solitary in the cavities.
Female capitula supported on a stout peduncle continuous with
the nerve of the frond, from 2 to many-flowered, orhiculate,
hemispherical or conical, generally lobate, paleaceous beneath,
chambered within the looali looking downwards. Involucre of
each loculus one or many-fiowered or none. Perianth arcuate,
delicate, split into equal segments, rarely absent. Pistillidia from
two to twelve set in two rows on a short receptacle. Calyptra
thin, often persistent only at the base. Capsule with a short
pedicel, globose, of one row of cells, either splitting all round
or 4-8-fid from the vertex. Elaters 1-5-spiral, deciduous.
Suborder III. EICCIACEA:.
Fronds cellulose, fleshy, furnished with a stratum of air-
cavities beneath the epidermis, in most instances dichotomous.
Fruit valveless, generally immersed in the frond. Involucre
most frequently and perianth always absent. Capsule either
free or connate and confused with the calyptra, globose, bursting
irregularly. Elaters none. Antheridia immersed in the frond.
Suborder IV. ANTHOCEEOTACEiE.
Fronds tender, slightly fleshy or thin, becoming flaccid by
drying, radiculose beneath but without paleae; orbicular, lobate
at the circumference, nerve very broad, confused with the lamina.