urve and uniform interval between each other in the same
species; their surface is either smooth, or sometimes it is invested
with minute warts or spinules.

In all the species of this genus, however, irregular and abnormal
elaters are occasionally met with among the typical ones. As these
abnormal forms always arrest attention, and have been conceived to
possess specific value, it may be well to note the principal of them.

1. The elater is sometimes branched. In two or three species the
branching appears to be quite regular and not abnormal; still, even in
these species, most of the elaters in the sporangia are not branched. In
some cases the branching arises from confluence of two or more elaters.

2. Ellipsoidal swellings, or enlargements of the elater, sometimes
occur, at one or both extremities, or at points intermediate between
them; these always occur irregularly, and are essentially abnormal.

3. The smooth tapering point is rarely wanting, in which case the
extremity presents a blunt end, the spiral ridges running to the end.
More frequently the tapering points are multiplied, the elaters bearing
two or three spines at the extremities; this often occurs in the species
of Trichia, and also of Hemiarcyria with spinulose elaters.

4. The spiral ridges are sometimes defective, there being less than the
typical number; sometimes they are merely displaced, there being a much
wider interval between them than usual; rarely do they habitually wind
about the thread in an irregular manner.

5. Under high magnifying power, fine ridges are sometimes seen running
lengthwise of the elaters, bridging the intervals between the spirals.
These were first observed by DeBary, in _Trichia chrysosperma_, but they
have since been seen in the elaters of nearly every other species of
Trichia, and also in species of Hemiarcyria.

The few species with elaters, so far as yet known, habitually irregular,
defective and abnormal, are referred to the genus Oligonema.

The normal species of Trichia arrange themselves quite naturally into
three sections.

Sec.1. A NACTIUM. Sporangia varying from globose to pyriform or turbinate,
supported on a more or less elongated stipe. Spores globose, the surface
minutely warted.

_a. Elaters with very long tapering extremities._

1. TRICHIA FRAGILIS, Sow. Sporangia obovoid to pyriform or clavate,
often fasciculate, stipitate; the wall a thin membrane, with a thick
dense outer layer of brown-red