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32G THREE NEW LASTREAS FROM ASSAM.
The most nearly-allied form to the above is my newly-proposed
species P. crassifuUiis, which has already been sufficiently discussed.
Then as true ftuitans-iovxn'i, i. e., as probable hybrids with
nntam as one parent, I would place certain continental forms which
present a strong resemblance to deep-water states of P. pohjgoni-
foiius. I can give no detailed account of these in the present place,
as this note is already far too long, but I will remark that P. variifolius
Thore may possibly come under this division of the group.
If continental botanists would carefully examine the waters where
Jlaitans-iovms grow I tliink they would soon be able to detect the
origin of any supposed hybrids between natans and pob/f/onifolius.
Herbarium specimens may serve to suggest such an origin, but the
question can only be solved by careful study of the living plants
and the conditions under which they grow.
It is with diffidence that I venture to suggest that further
evidence is required before tlie Neckar plant can be safely admitted
to be a, Jluitans-fonn at all; judging from the dried specimens of
fruits and foliage I have seen of ''imitiugjluitans," I think it is
probable that we have in these plants one or more good species
whose true position would be between natans and itohjtfonifoUas, and
which probably are not hybrids at all.
Explanation of Plate. — 1. Upper leaves and flowering spike. 2. Lower
leaves ; a, phyllode. 3. Detached stipule bearing a leaf.
THREE NEW LASTREAS FROM ASSAM.
By C. W. Hope.
Nephrodium (Lastkea) assamense, n. sp. — Caiidex erect
stipes closely tufted, 8-15 in. long, densely clothed at base with
linear acuminate blackish or brown scales, and furnished above, as
are the rachises, with few or many broad-based long narrow hair-
pointed dark brown scales ; fronds lanceolate or subdeltoid, 9-15 in.
long, 5-7 in. broad, bipinnatifid or bipiunate towards base of pinna,
towards apex suddenly diminishing in width, lowest pair of pinnae
sometimes nearly as long as next pair, major pinnje distant 4-6
pairs pinnae patent or much inclined upwards, lanceolate, acumi-
;
nate, sometimes broadest at base, but there sometimes much
narrowed, lowest hardly ever at all unequal-sided, and hardly more
compound than others, pinnatifid to a winged rachis into oblong
subspatulate segments ^1^ in. long by ^-f in. wide, somewhat cut
away on upper side and decurrent on rachis on lower side, bluntly
rounded and sharply toothed at point, rarely slightly pinnatifid at
base in largest specimens ; segments subentire, with teeth on both sides
or distinctly lobcd, one lobe to each group of veins with a sharp
sometimes double tooth ; texture herbaceous, both surfaces glabrous ;
veins, except costa, rarely visible on upper side, but all very distinct
against the light, forked or pinnate in the lobes, bipiunate in lowest
lobes, all terminatiug within the margin, fertile veinluts often much