eter. See Plate III, Fig. 10.

Growing on old wood. AEthalium from 1 to several centimeters in extent
and 5-10 mm. in thickness, usually growing singly, rarely close enough
to be confluent. This species has lately been referred to _Reticularia
rozeana_, Rost., but it varies greatly from the account given of that
species in the Journal of Botany for September, 1891.

2. RETICULARIA UMBRINA, Fr. AEthalium pulvinate, roundish, more or less
irregular, the surface covered by a thin, silvery, shining, common
cortex, which at the base is confluent with the hypothallus. Walls of
the sporangia umber or rusty-brown next the base, with broad expansions
in places thickly grown together, toward the surface passing into narrow
bands and abundant fibrous threads, which rapidly disintegrate. Spores
in the mass umber or rusty brown, globose, most of the surface
reticulate, 7-9 mic. in diameter.

Growing on old trunks. AEthalium one to several centimeters in extent,
and 5-15 mm. in thickness. The walls of the sporangia are much more
reduced to the shreddy fibrous condition than in the preceding species,
and on this account they much more rapidly disintegrate, causing the
aethalium soon to collapse. It is _Reticularia Lycoperdon_, Bull.

3. RETICULARIA ATRA, A. & S. AEthalium pulvinate, variable in form and
size, covered with a thin, fragile, blackish, cortical layer. Walls of
the sporangia violaceous, next the base with broad expansions, in places
more thickly grown together, toward the surface becoming narrow with
more abundant fibrous threads, sometimes presenting a loose irregular
network, the whole structure, however, quite variable, according to the
stage of the disintegration. Spores globose, violet, minutely warted,
14-16 mic. in diameter.

Growing on wood and bark, especially of pine. AEthalium 2 or 3 to several
centimeters in extent. This is _Amaurochaete atra_ of Rostafinski's
monograph, but the structure appears to be altogether similar to that of
_Reticularia umbrina_.

II. CLATHROPTYCHIUM, Rost. AEthalium composed of numerous regular erect
sporangia, seated in a single compact stratum, on a well-developed
hypothallus, the surface formed by the coherent apices. Sporangia at
first cylindric, with the apex convex and the wall entire; soon, by
mutual pressure, they become prismatic and the lateral faces disappear,
leaving the edges and the apex permanent. Spores globose, ochraceous.

1. CLATHROPTYCHIUM RUGULOSUM, Wallr.