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I have given the author’s own diagnosis of the species.
Scattered in cracks of the bark, from S —1 mm. high, sometimes
a little more, stem suberect, sometimes rather flexuous,
sporangium very small.
C l a t h e o p t y o h iu m , E o s t.
Aethalium naked ; sporangia sessile, prismatic or cylindrical,
densely crowded on a hypothallus, walls of sporangia persistent
at the apex, lateral walls reduced to .5—6 slender threads which
extend from the hypothallus and support the apical portion.
Rost., Mon., p. 225 ; Cooke, Myx. Brit., p. 55 ; Schroeter,
p. 164 ; Sacc., Syll., p. 405 ; Zopf, p. 137.
Rostafinski was the first to point out the true aethalioid
nature of Glathroptyehvmn mgulosuni, and in his diagrammatic
arrangement, Mon., fig. 30, represents the sporangia as circular
in outline, packed close together, and consequently leaving
triangular interspaces; each sporangium is represented as
having six triangular thickened portions of its wall projecting
into the intei’ior of the sporangium. A careful examination of
several specimens in various stages of development show th at
Rostafinski’s interpretation is not correct. The sporangia, when
young, are cylindrical, with both ends slightly convex, and the
walls entire; towards maturity the lateral walls, due to mutual
pressure, become flattened, and the sporangia are then hexagonal
or rarely pentagonal in transverse section ; at the angles where
three contiguous cells meet the walls of the sporangia become
thickened, agglutinated together, and persist as the upright
threads that support the slightly convex, persistent, cap-like
portions of the sporangia. From the above description it will
be seen that the triangular upright threads correspond in
position to the triangular interspaces in Rostafinski’s diagram,
and further, that the black triangular thiokeuings shown in
the diagram have no existence in nature. During the period
between the formation and maturing of the spores, the flat
lateral walls of the sporangia are dissolved, with the exception
of a narrow jagged wing projecting from each angle of the
upright permanent portions. In G. rugulosum these wings are
very rudimentary, but in G. BerheUyi are often broader than
the triangular portion, and recalling to mind the similar structure
in Enteridium olivaceum. The triangular upright threads
almost invariably show traces of a central cavity, which corresponds
to the intercellular space between the originally
cylindrical sporangia. The persistent apices of the sporangia,
when viewed from above under a low power, are seen to consist
of very slightly convex hexagons, rarely pentagons, so firmly
agglutinated together that the whole can be removed as a
continuous membrane ; if this is done, and the membrane then
viewed from the under side, after the spores have been cleared
away, the stumps of the triangular threads will be seen to
originate from the angles where the permanent apices of three
sporangia meet ; if this membrane is treated with potassie
hydrate, the apices separate from each other as do also the
triangular threads ; this separation sometimes takes place in
water alone, when the apices with their threads appear as
represented in Eostafinski’s figures 28 and 29.
The above account applies to the typical structure, but both
species appear to be very variable. Zopf has figured an aherrent
form of G. rugulosum, having the threads supporting the apical
persistent portion of the sporangium varying in number, irregularly
branched and anastomosing. I have met with a 'similar
form, also another variety where the threads are branched and
anastomosing and not confined to the margin of the apical
portion, but originating from any portion of its under surface,
and approximating so closely in structure to certain forms of
the genus Perichaena as to lie almost indistinguishable.
Distrib. Europe; Africa; India; Ceylon; Australia; United
States : species S.
Clathroptychium rugulosum, Rost. (f. 25—28).
Hypothallus well developed, often extending as a whitish
membrane for some distance ; sporangia prismatic, apex slightly
rounded, and supported bj- five or six slender triangular persistent
threads, the fiat face pointing to the interio'r of the sporangium
rugulose ; colour of mass of sporangia reddish, bright