the apex
downward. Stipe long, slender, tapering upward, flexuous, bent or curved
at the apex, yellow, yellow-brown, or pale brown. Capillitium of very
slender tubules, forming a loose net-work, scarcely expanded at the
angles; the nodules of lime small, white or yellow, roundish or obtusely
angular, few to numerous, rarely wanting. Spores globose, very minutely
warted, violaceous, 8-10 mic. in diameter.

Growing on old wood, bark, mosses, etc Sporangium .2-.4 mm. in diameter,
the stipe 1-2 mm. in length, the lime nodules when abundant once to
twice the diameter of the spores, when scanty very small. This, as I
find it growing, is an extremely variable species; I think its various
forms and appearances cover such species as _Didymium obrusseum_ B. &
C.; _D. tenerrimum_ B. & C.; _Physarum tenerum_ Rex, etc., etc.

4. PHYSARUM NUCLEATUM, Rex. Sporangium globose, stipitate, erect or
slightly nodding; the wall a thin, pellucid membrane, thickly covered
with minute, white, roundish scales of lime, which are exceptionally
sparse or absent, rupturing irregularly. Stipe long, slender,
yellowish-white, longitudinally rugulose, tapering upward, expanded at
the base into a small hypothallus. Capillitium of very slender tubules,
forming a delicate net-work of small meshes, scarcely expanded at the
angles; nodules of lime small, not numerous, roundish, white, usually
concentrated into a large lump in the center of the sporangium. Spores
globose, very minutely warted, violaceous, 6-7 mic. in diameter.

Growing on old wood, bark, etc.; rare. Sporangium .4-.5 mm. in diameter,
the stipe two or three times as long, the lime-nodules about the size of
the spores. The species much resembles some of the forms of _P.
obrusseum_, but is to be distinguished by its central mass of lime and
the small spores.

5. PHYSARUM COMPACTUM, Wingate. Sporangium depressed-globose, the base
slightly umbilicate, stipitate, cernuous; the wall a thin, violaceous
membrane, rugulose and iridescent, studded with large and thick,
snow-white, roundish or elliptic scales of lime, at maturity splitting
from the apex downward into several segments. Stipe long, rather weak,
bent and flexuous, tapering upward, longitudinally rugulose, from
snow-white to whitish-ochre and smoky-white, usually brownish at the
base, and arising from a thin hypothallus. Capillitium a delicate
net-work of very slender threads, with no expansions at the angles; the
lime mostly concentrate