rangium as a columella. Capillitium
of slender tubules, arising from the columella, repeatedly branching and
anastomosing to form a regular net-work, the extremities attached on all
sides to the wall of the sporangium, the tubules containing at intervals
nodules of lime. Spores globose, violaceous.

This genus is readily distinguished from _Physarum_ by the columella,
which gives origin to the capillitium; this feature indicates a
relationship to _Didymium_ and to _Lamproderma_.

Sec.1. EUCYTIS. Sporangium globose, the columella not reaching its center.

1. CYTIDIUM PULCHERRIMUM, B. & R. Sporangium globose, stipitate; the
wall a thin lilac-tinted membrane, with a dense closely adherent layer
of granules of lime, dark purple or wine-colored. Stipe long, erect,
dark purple to purplish black, tapering upward and entering the
sporangium as a slight obtuse columella. Capillitium of slender lilac
tinted threads, forming a dense net-work of very small meshes, with
slight expansion at the angles; the nodules of lime very small,
numerous, dark purplish or vinose in color, ellipsoidal or obtusely
angular. Spores globose, even, lilac, 7-9 mic. in diameter.

Growing on old wood. Sporangium .4-.5 mm. in diameter, the stipe two or
three times as long; the lime-nodules about the size of the spores. The
purple stain, which the sporangia leave on white paper, is made by the
granules of lime; the spores color the paper violet. _Physarum
pulcherrimum_ B. & Rav., and _P. atrorubrum_ Peck.

2. CYTIDIUM CITRINUM, Schum. Sporangium globose, the base slightly
flattened or umbilicate, stipitate; the wall a thin membrane, covered
with small scales of lime, yellow or greenish-yellow, breaking up and
falling away at maturity. Stipe stout, erect, yellow, longitudinally
rugulose, expanded at the base, tapering upward and entering the
sporangium as a short obtusely conical columella. Capillitium of slender
tubules, forming a dense net-work, with slight expansions at the angles;
the lime-nodules numerous, roundish or ellipsoidal, variable in size,
yellow. Spores globose, nearly smooth, violaceous, 7-8 mic. in diameter.

Growing on bark, leaves, mosses, etc. Sporangium .5-.6 mm. in diameter,
the stipe from once to twice this length. This, the typical species, I
have not seen in this country, but forms with the sporangium
lemon-yellow and grayish-yellow, with the stipe golden-yellow, connect
it with _C. rufipes_. It is _Physarum citrinum_ Schum. _D