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 mu.

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_.

1892. _Didymium farinaceum_ Schr., var. _minus_, List., _Mycetozoa_,
p. 97.
1896. _Didymium minus_ List., Morg., _Jour. Cin. Soc._, p. 61.
1899. _Didymium minus_ List., Macbr., _N. A. S._, p. 89.

Sporangia gregarious, depressed-globose, umbilicate below, whitish or
gray, small, about 1/2 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 mu.

Probably more common than the preceding, and generally mistaken for it.
Distinguished by its smaller size, longer and more slender stem, and
general trim, well-differentiated appearance. Certainly very near the
preceding, of which Mr. Lister regards it as merely a variety. Professor
Morgan thought it in this country the more common form.

New York, Ohio, Iowa; reported from Europe, Africa, South America.

9. DIDYMIUM CLAVUS (_Alb. & Schw._) _Rabenhorst._

1805. _Physarum clavus_ Alb. & Schw., _Consp. Fung._, p. 96.
1829. _Didymium melanopus_ Fries, _Syst. Myc._, III.,