Sporangia gregarious, stipitate, globose, or slightly depressed above, pale blue-gray or pure white; stipe sometimes equal to the sporangium, generally longer, slender, slightly wrinkled, white, or yellow, pallid, when longer tapering upward; columella white, conical, sometimes obsolete; hypothallus none; capillitium dense, but delicate, persistent, a close network of hyaline threads, with white or yellowish nodes sparingly thickened and calcareous, many without lime; spore-mass brown; spores by transmitted light, violet, minutely warted, 7.5-9 mu. Plasmodium greenish-yellow. This species, very common eastward, rare west of the Mississippi, is at once very beautiful and very variable. Its several phases have been again and again observed and described too often by distinct specific or varietal names. A form from New York, with long, white stems and almost pure white sporangia, is _P. albicans_ Peck. Forms occur like _P. albicans_, but flushed with _rose_ throughout. From New England, specimens sent Rostafinski were by him deemed a variety of _P. petersii_ Berk. & C., and called _P. petersii_ var. _farlowii_ Rost. By this name the species has been generally distributed in this country. _N. A. F._, 1120. Most gatherings of this species have small, somewhat ochraceous, sporangia, and pale yellow, or somewhat rusty, stipes. These latter, with somewhat heavier stem, represent _Physarum simile_ Rost. A form collected sparingly in Iowa has short, white stipes and blue gray sporangia one-third larger than observed in the eastern types. This was recorded, _l. c._, as _P. columbinum_ Macbr.; name already in use. The spores in the Iowa specimens are also a little larger, 8-10 mu. Pale cyanic and roseate forms also sometimes occur in late fruitings; see next species. In all phases the persistent tenacity of the capillitium is a striking characteristic well noticed by Fries (_l. c._, p. 101): "Peridia a gleba omnimo libera, dein tota diffracta, evanescentia, ... capillitio compacto forma servata persistente." The peridium, except a small part below, all falls away, leaving the capillitium apparently intact, crowded with spores. From England to Iowa; Canada, south to Louisiana and Mexico; apparently, in one form or another, cosmopolitan. 22. PHYSARUM LILACINUM _Sturgis & Bilgram._ 1917. _Physarum lilacinum_ Sturg. & Bilg., _Mycologia_, Vol. IX., p. 323. Sporangia gregarious, stalked, globose, erect, pale-lilac to pale Indian-red in color, 0.5 mm. in diameter; sporangium-wall membranous, beset with rounded masses of lilac or reddish lime. Stipe erect, broad-based, tapering upwards, calcareous, furrowed, paler than the sporangium or concolorous, 0.7-0.9 mm. long, about 0.1 mm. thick, columella conical or columnar, capillitium delicate, rigid, persistent; lime-knots small, rounded, composed of large, pale lilac, or reddish, spherical granules. Spores pale-brown, almost smooth, 8-9 mu. Vicinity of Philadelphia,--Bilgram.