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 concentrated in one large, snow-white nodule at the center, a few very small, roundish nodules scattered through the net-work. Spores globose, very minutely warted, violaceous, 7-9 mic. in diameter. Growing on old wood, mosses, etc.; a common species. Sporangium .4-.5 mm. in diameter, the stipe two or three times this length. _Tilmadoche compacta_ Wingate. It is doubtful if _Tilmadoche columbina_ Rost. belongs to this species. According to Lister, _Lepidoderma stellatum_ Massee, is the same as this species, and if it be objected to the name that there is already a _Physarum compactum_ Ehrenberg, it may have to be called _Physarum stellatum_. _b. Sporangium more or less irregular_.