I
of a double row of elevated points. Tbeir surface is very
rough from the presence of these points, which consist of a
coating of crystallized siliceous particles. In this species
the sheaths fit closely around the stems, so that they are
nearly cyhndrical ; they are marked by ridges of the same
number as those on the stem, but less prominent, and they
terminate in a series of teeth equal in number to the ridges,
the teeth being black, membranous, and bristle-shaped, soon
falhng off, and leaving the margin crenated. The sheath
immediately below the cone of fructification has, however,
its teeth persistent, and it is somewhat funnel-shaped. The
sheaths are at first pale green with a black margin ; from
this they change to be entirely black ; and finally they become
whitish in the middle, leaving a narrow ring of black
at the base and margin.
In this species a section of the stem shows on the exterior
a series of distinct ridges, formed of twin projections, and
varying in number, as has been already explained ; opposite
to the furrows, between them, and occupying about the centre
of the solid cylinder, is a ring of moderate-sized cavities.
The central cavity is comparatively large.
The cones of fructification are comparatively small, and
are seated on the apices of a number of the stems ; they are
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