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colour of the spores as seen in the mass, passing in some species
to deep orange and orange-brown; similar colours are met with
in tlie sporangia] wall. In the genus Pericliaena the inner
surface of the sporangial wall is frequently covered with a layer
of amorphous granules of lime. In stipitate forms of some
species belonging to the genera Arcyria, Heterotricliia, and
Trichia, the stem is filled with cells which are either spherical
or polygonal from mutual pressure. These cells, when young,
contain pi'otoplasm, and the wall gives a cellulose reaction;
they are usually largest at the base of the stem, and become
smaller upwards, passing insensibly into normal spores at the
point where the stem expands into the sporangium. The tubes
of the capillitium frequently pass down between these cells
into the stem. I t would appear as if the stem cells had
originally been intended for true spores, hut owing to the
contraction of the base of the sporangium into a stem had been
checked in their development.
T r ic h ia .
O l ig o s em a .
P b o t o t r ic h ia ..
L ycog.a la.
'P e r ic h a e n a .^
A r c y r ia .
H e t e r o t r ic h ia .
L a c h n o b o lu s .
— Op h io t h e o a .
CALOTRICHEAE.
/C l a t h r o p t y o h iu m .X
\PERITEICHEAE./
ANALYSIS OF THE GENERA.
CALOTRICHEAE.
Sub-sect. TaiCHEAE.
Platers free, not forming a network.
T e ic h ia . Elaters with well-developed spirals.
O l ig o n e j ia . Elaters without distinct spurals.
Sub-sect. A e c y r ia e .
Elaters attached to wall of sporangium only slightly branched
or forming a network.
P r o t o t r ic h ia . Elaters fixed by one end to base of sporangium,
tips free.
P e r ic h a e n a . Sporangial wall with a layer of lime granules
inside; capillitium scanty.
OjMothcca. Threads of capillitium usually spiny, of equal
thickness, forming a net with numerous blunt, free arms.
EetcrotrieUa. Threads of capillitium of two distinct thicknesses,
forming a net, outer network with numerous free,
pointed arms.
Lachnobolus. Threads of capillitium forming a network
attached at numerous points to wall of sporangium.
A r c y r ia . Threads of capillitium forming a network usually
elastically protruded at maturity.
L y c o g a la . Cortex containing numerous cells filled with
protoplasm, capillitium tubes thick.
Sub-sect. A r c y r ia e .
P e r ic h a e n a , Fries.
Sporangia sessile, gregarious, dehiscing irregularly or in a
circumscissile manner, wall usually double, the outer often
containing granules of lime or a layer of granules of orp n ic
m atter; capillitium variously developed, m some species form-
ino- an irregular network attached at various points to the upper
portion of sporangial wall, in other spedes almost obsolete,
threads of the capillitium without definite markings, either
quite smooth or with a few scattered, rudimentary spmules or
iiotch-like constrictions; spores globose.
Perichaena, Fries, Gast,, p. 12; Eost., Mon., p. 292; Cooke,
Myx. Brit., p. 77; Zopf, p. 169; Saoc.. Syll, vii. pt. I , p. 420.
The most prominent generic features are the circumscissi e
dehiscence of the sporangium, which however is not universal,
the layer of amorphous particles of lime or of organic ^matter