stinct fibrous thickenings
upon the inner surface, the membrane, or at least certain portions of
it, disappearing usually at the maturity of the spores, leaving behind
the more permanent fibrous thickenings as a more or less definite
capillitium. Spores globose, purple, brown, ochraceous, rarely
violaceous.

In this order the threads of a capillitium first make their appearance;
but they are confined to the inner surface of the wall of the
sporangium, being set at liberty by the early decay of the outer
membrane.

TABLE OF GENERA OF RETICULARIACEAE.

_a. AEthalia._

1. RETICULARIA. AEthalium composed of numerous slender sinuous sporangia
which repeatedly branch and anastomose.

2. CLATHROPTYCHIUM. AEthalium composed of numerous regular erect
sporangia.

_b. Sporangia simple._

3. CRIBRARIA. Capillitium of slender threads combined into a network of
polygonal meshes.

4. DICTYDIUM. Capillitium of numerous convergent ribs, which extend from
base to apex, and are united by fine transverse fibers, thus forming a
network of rectangular meshes.

I. RETICULARIA, Bull. AEthalium composed of numerous slender sinuous
sporangia, which repeatedly branch and anastomose, closely packed
together and seated upon a common hypothallus, the apices of the final
branches coherent at the surface, and naked or covered by an additional
corticate layer. Walls of the sporangia consisting of a thin membrane,
with abundant fibrous thickenings, presenting broad expansions,
narrowing to thin flat bands, and reduced in many places to slender
fibrous threads. Spores abundant, globose, umber or violaceous.

After the maturity of the spores disintegration of the sporangial wall
begins, the thin membrane disappearing more rapidly than the fibrous
thickenings or the portions of the sporangial walls near the base, which
are more compactly grown together; there is thus left at each stage an
increasing number of the shreddy fibers mingled with the spores.

1. RETICULARIA SPLENDENS, Morg. n. sp. AEthalium pulvinate, circular or
more or less elongated and irregular, seated on a conspicuous silvery
hypothallus; the surface naked, bright umber, smooth and shining. Walls
of the sporangia firm and quite persistent, pale umber, slowly
disintegrating, consisting for the most part of wide expansions, with
their angles tapering to narrow bands and slender threads. Spores in the
mass pale umber, globose, most of the surface reticulate, 7-9 mic. in
diam