t I can see no difference in the spores.

5. DIDERMA GLOBOSUM, Pers. Sporangia subglobose, more or less irregular
from mutual pressure, closely crowded together on a thick, white
hypothallus, seated upon it or usually sunk into its substance at the
base; the wall with a white, smooth, and polished crustaceous outer
layer of lime, distinct and separable from the inner membrane, easily
breaking into fragments, and falling away: the inner membrane very thin,
rugulose, cinereous with granules of lime or free from them and
iridescent. Columella white, small, irregular, subglobose or
ellipsoidal, rarely wanting. Capillitium of slender, dark colored
threads, more or less branched and combined into a loose net. Spores
globose, very minutely warted, violaceous, 8-10 mic. in diameter.

Growing on old leaves. Sporangia .5-.8 mm. in diameter, the surface
smooth and polished.

6. DIDERMA CRUSTACEUM, Peck. Sporangia subglobose, irregular from mutual
pressure, closely crowded together on a thick, yellowish-white common
hypothallus, and at the base confluent with its substance; the wall with
a creamy white, smooth, crustaceous outer layer of lime, distinct and
separable from the inner membrane, and easily breaking up and falling
away; the inner membrane very thin, rugulose, cinereous and iridescent.
Columella whitish or cream colored, small, irregular, subglobose or
ellipsoidal, often wanting. Capillitium of slender, uneven, dark colored
threads, branched and combined into a loose net. Spores globose,
minutely warted, violet-black, opaque, 12-15 mic. in diameter. Plate
XII, Fig. 45.

Growing on old leaves, sticks, etc. A common species in this country.
Sporangia .7-1.0 mm. in diameter, the surface even but finely
pulverulent rather than polished. _Chondrioderma affine_, Rost., is said
to be the same species. It is readily distinguished from _D. globosum_,
by the much larger spores.

Sec.3. ASTROTIUM. Sporangia gregarious, scattered, or sometimes crowded and
confluent, often much depressed, sessile, rarely stipitate; the
hypothallus none or very scanty.

7. DIDERMA MICHELII, Lib. Sporangia orbicular, very much depressed,
often umbilicate above and concave underneath, stipitate or sessile,
gregarious, with the margins of the sporangia sometimes confluent. The
wall with a white crustaceous layer of lime, which soon ruptures around
the edges, allowing the upper part to break in pieces and fall away; the
inner membrane cinereous, rup