angium.
Spores globose, minutely warted, dark violaceous, 9-10 mic. in diameter.

Growing on wood, bark, and mosses. Sporangia .8-1.0 mm. in diameter,
more or less irregular. The wall of the sporangium is exactly like that
of certain species of _Diderma_. This species must be rare, as I have
met with it but twice in ten years, and I am not aware that it has ever
been found by any one else.

VIII. FULIGO, Haller. Aethalium a compound plasmodiocarp; the component
sporangia branching and anastomosing in every direction, complicate and
grown together; the walls of the sporangia a thin membrane, coated with
minute, roundish granules of lime. Capillitium of tubules forming a
net-work of irregular meshes, more or less expanded at the angles, the
tubules containing in greater or less abundance irregular nodules of
lime. Spores globose or sometimes ellipsoidal, violaceous.

The genus is readily distinguished from _Spumaria_ by the round granules
of lime upon the walls of the sporangia.

Sec.1. AETHALIUM, Link. Aethalia large; the lime in the capillitium scanty,
the nodules small, ellipsoidal, or fusiform.

_a. Aethalium with a thick fragile common cortex._

1. FULIGO RUFA, Pers. Plasmodium a large soft mass with a peculiar odor
and golden yellow in color. Aethalium very large, pulvinate, orbicular,
elongated, or quite irregular, extremely friable, the surface tawny or
ferruginous to ochraceous and whitish. The long narrow, sinuous
sporangia closely compacted, entirely grown together and inseparable,
covered by a thick common cortex, and seated on a much thickened
hypothallus; walls of the sporangia a thin pellucid membrane, coated by
a thin layer of white granules of lime. Capillitium of very slender
tubules, extending across from wall to wall, sparingly branched and
scarcely forming a network, not at all or only slightly expanded at the
angles; the tubules for the most part empty, here and there with slight
fusiform or elongated swellings containing granules of lime,
occasionally bearing roundish or ellipsoidal nodules of larger size.
Spores globose, nearly smooth, violaceous, 6-9 mic. in diameter.

Growing on old trunks in woods in great abundance from early Spring to
Winter. Aethalium 3-6 or sometimes many centimeters in extent and 1-2
cm. in thickness. The common cortex and the hypothallus are a millimeter
or more in thickness; they are composed of successive layers of thin
plates of membrane coated with granules of