Sporangia gregarious, hemispheric, depressed, umbilicate below, stipitate or sessile; the peridium firm, dull brown in color, frosted with minute crystals of lime, breaking irregularly; stipe, when present, short, stout, dull black, opaque, arising from a broad base or hypothallus; columella large, prominent; dark-colored, rough above, concave below; capillitium of more or less sinuous, usually dark-colored threads, sparingly branched, and often with calyciform thickenings; spore-mass black, spores by transmitted light pale, purplish-gray, spinulose or rough, 10–12 µ.

A well-marked and common species, distinguished by its depressed sporangium and dark-colored, opaque stipe. The latter is usually very short, almost completely concealed in the concavity of the umbilicate sporangium. The columella is dark-colored, forming the floor of the peridial cavity.

Persoon first named this species as here. Later on, Uster's Ann., XV., 6, he substituted villosum as a more appropriate specific name. Schrader rejects both names given by Persoon as unsuitable, and suggests farinaceum. Schrad., op. cit., p. 27.

New England, Ohio, Missouri, Alabama, Iowa, Nebraska; Europe; probably cosmopolitan.

8. Didymium minus Lister.

[Plate X.], Figs. 4, 4 a, 4 b.

Sporangia gregarious, depressed-globose, umbilicate below, whitish or gray, small, about ½ mm., stipitate; stipe erect, rather slender, black, faintly striate, about equal to the sporangium in the horizontal diameter; columella distinct, dark brown, globose or depressed-globose, attaining in some cases the centre, rough; capillitium delicate, almost colorless, radiating, sparsely branched; spores in mass dark brown, by transmitted light violet-tinted, minutely roughened, 8–10 µ.