V "A Si
spherical, but when the lid is cast o ff it becomes urn-shaped or
cylindric, and the mouth never exhibits any trace o f peristome ; the
walls are brittle and bear numerous stomata on the surface, and
when ripe are o f a deep chestnut brown colour.
T h e operculum or lid is flattened or in form o f an inverted
saucer, and is cast off by contraction o f the capsule with a crackling
noise or slight explosion, and at the same time the spores are
driven forth by compression o f the capsule walls. Not unfrequently
the lid remains attached by one margin, which acts as a hinge, and
the capsule is closed again when moistened. I f the capsule remains
submerged or always wet, the lid does not open, but the capsule
falls away from the vaginula and a hole is left at the base, the
columella decays and the spores can escape in this way, or it
happens that they germinate while still enclosed in the capsule
and burst it b y expansion, or the lid may be forced off and the
capsular wall only left with a hole at each pole, and such barrelshaped
shells we frequently meet with in our examination o f
Sphagnum tufts.
T h e spore sac differs in shape from that o f the true mosses,
for it is in form o f a hollow hemisphere, occupying the upper part
o f the capsule and resting on the top o f the columella to which its
inner wall is united, while the outer wall coheres to the inner cell-
layer o f the capsule wall. When mature, the columella breaks
away from the vaulted under side o f the spore sac and shrivels
back to the base o f the capsule, leaving an empty space, which is
probably concerned in the bursting o f the capsule.
T h e two kinds o f spores are found in the same capsule or
in different ones. T h e large spores va ry between and 4}
hundredths o f a millimetre in diameter, and in colour present various
shades o f yellow, ochraceous, or ferruginous brown ; the exospore
or external coat is covered with scattered papillee.
C H A P T E R V .
ARRANGEMENT OF THE SPECIES.
I t is always convenient to distribute the species o f a genus into
groups or sections, especially when they happen to be numerous
and dififlcult o f diagnosis ; this has been attempted with respect to
the Sphagna in various ways b y different authors, and it may be
o f advantage to present an outline o f each of these.
B r id e l , in his Bryologia Universa (1826) arranged his sixteen
species as follows, classing them as Musci Evaginulati Cladocarpi:—
1. Ramuli distinctly fasciculate.
a. Lea ve s broader, rather obtuse.
S. cymbifolium tenellum,squarrosum, contortum, sub secundum,
immersum, oblongum, macrophyllum, denticulatum.
b. L ea ve s narrower, rather acute.
capillifolium, recurvum, cuspidatum.
2. Ramuli indistinctly fasciculate.
compactum, ericetorum, condensatum, subulatum.
C. M ü l l e r , in his valuable Synopsis Muscorum (1848), made a
great advance on the writings o f previous authors by introducing
the cell structure o f the leaves into the specific character o f these
mosses. H e points out the differences in the leaves o f the stem,
branches, and peduncle, and the presence or absence o f spiral
fibres in them.
1. L ea ve s without annular fibres.
6". sericeum, macrophyllum.
2. Leaves with annular fibres.
a. L ea ve s rounded at apex.
.S', cymbifolium, &c.
b. L ea ve s truncate.
* Peduncular leaves without spiral fibres.
N. molluscum, squarrosum, cuspidatum, acutifolium, &c.
** Peduncular leaves with spiral fibres.
N.laxifolium,compactum,molluscoides,subsecundum, &c.
A ll the species are said erroneously to be dioicous.