olored threads, radiating from the columella
and sparingly branched. Spores globose, with minute scattered warts,
dark violaceous, 9-11 mic. in diameter. Plate XII, Fig. 44.

Growing on old wood of oak, hickory, etc., late in Autumn. Sporangium
.7-1.0 mm. in diameter before dehiscence, the stipe usually longer than
the sporangium. The color of stipe, columella and sporangium varies from
white through yellowish to brown; the spores are quite peculiar by
reason of their prominent scattered warts. I do not think _Chondrioderma
Lyallii_, Massee, can be maintained as a separate species.

Sec.2. STROMNIDIUM. Sporangia growing closely crowded together upon a thick
highly-developed calcareous common hypothallus, either seated upon it or
partially imbedded in its substance; the wall rupturing irregularly.

3. DIDERMA SPUMARIOIDES, Fr. Sporangia rather small, irregularly
subglobose, sessile, seated close together on a strongly-developed
whitish or yellowish common hypothallus; the wall white, rugulose,
covered by a dense farinaceous layer of lime. Columella convex,
roughened, white or yellowish, sometimes scarcely developed. Capillitium
rather scanty, of slender colorless threads, sparingly branched,
ascending from the columella. Spores globose, minutely warted,
violaceous, 8-10 mic. in diameter.

Growing on old leaves, bark, moss, etc. Sporangia .4-.6 mm. in diameter,
irregular and rugulose. On account of the pulverulent coat of lime on
the sporangium, Massee refers the species back to Didymium, where it was
placed by Fries.

4. DIDERMA STROMATEUM, Link. Sporangia large, subglobose, depressed,
irregular and angular from mutual pressure, closely crowded together on
a thick yellowish or pinkish common hypothallus; the wall smooth and
even, grayish-white or cinereous, with a thin closely connate outer
layer of minute granules of lime. Columella considerably elevated or
much depressed, convex, subglobose or quite irregular, white or colored,
as the hypothallus, especially at the base. Capillitium of abundant
colored threads, more or less branched and combined into a loose net.
Spores globose, minutely warted, violaceous, 8-10 mic. in diameter.

Growing on Hickory bark. The sporangia .5-.8 mm. in diameter, the
surface smooth. Rostafinski, in his Monograph, places this species as a
variety of _D. spumarioides_, but in the Appendix it is separated as a
species. The sporangia are quite different from those of _D.
spumarioides_, bu