kish, breaking up and falling away at maturity. Stipe
variable in length, white or smoky-white, usually darker below, rising
from a thin hypothallus, tapering upward and entering the sporangium as
a short obtuse or conical columella. Capillitium of slender tubules,
forming a dense, persistent net-work of very small meshes, more or less
expanded at the angles; the nodules of lime variable in size, numerous,
white, roundish, ellipsoidal or obtusely angular. Spores globose, nearly
even, pale violaceous, 7-9 mic. in diameter.

Growing on old wood, bark, mosses, etc. A very common and abundant
species. Sporangium .5-.6 mm. in diameter, the stipe from once to two or
three times this length. The lime nodules in the capillitium are
sometimes round and quite minute, then again they are large and obtusely
angular; the columella varies from very short and conical to longer and
more cylindric. _Diderma globuliferum_ of Fries S. M., _Physarum
albicans_ Peck. The specimens with the columella well nigh obsolete, may
be _Tilmadoche columbina_ Rost.

6. CYTIDIUM MELLEUM, B. & Br. Sporangium globose, stipitate or
subsessile; the wall a thin yellowish membrane, rugulose, covered by
large irregular scales of lime, honey-color to golden-yellow, breaking
up irregularly. Stipe short, sometimes very short or nearly obsolete,
snow-white, expanding at the base into a small white hypothallus,
tapering upward and entering the sporangium as a short obtusely conical
columella. Capillitium a loose net-work of delicate tubules with broad
vesicular expansions containing much lime; the nodules numerous, white
or sometimes yellow, large, irregular, lobed, and branched. Spores
globose, nearly even, pale violaceous, 7-9 mic. in diameter.

Growing on old leaves, sticks, herbaceous stems, etc.; not uncommon in
this region. Sporangium .4-.5 mm. in diameter, the stipe about the same
length or much shorter. _Didymium melleum_ B. & Br. _Didymium
chrysopeplum_ B. & C. also belongs here and not with _C. citrinum_.

Sec.2. REXIELLA. Sporangium ellipsoidal or pyriform, the columella
prolonged nearly to the apex of the sporangium.

7. CYTIDIUM PENETRALE, Rex. Sporangium ellipsoidal or pyriform,
stipitate; the wall a thin pellucid membrane, covered with small scales
of lime, yellow-gray to greenish-yellow, rupturing at maturity into two
to four segments. Stipe long, slender, translucent, pale red to dark red
in color, tapering upward, entering the sporangium and p