Sporangia depressed, globose, or irregular, sessile, more or less aggregated, ochraceous-yellow, peridium double, the outer, thick, cartilaginous, at length irregularly ruptured, and reflexed, disclosing the more delicate, ashen-gray, inner membrane which encloses capillitium and spores; capillitium abundant, showing large, white irregular calcareous thickenings which are often consolidated in some sporangia tend to aggregate at the centre; spore-mass brown, spores violaceous, slightly roughened, 8-10 mu. This beautiful species shows a peridium as distinctly double as in any diderma. The outer peridium is reflexed exactly as in some species of that genus; is yellow without, white within, and withal long persistent. The capillitium of course distinguishes the species instantly as a physarum. By the size of the spores it is distinguished from the species preceding. This being a decisive specific character the synonymy prior to Rostafinski is somewhat uncertain. The specific name adopted by the Polish author is therefore approved, although perhaps not the earliest. Rare. The only specimens thus far are from Tennessee and Louisiana. 11. PHYSARUM MORTONI _Macbr. n. s._ PLATE XX., Figs. 2, 2 _a_. Sporangia gregarious, clustered but distinct, sessile small, about .75 mm., bright yellow, peridium double. The outer rough, breaking up into comparatively few rather large deciduous scales, the inner peridium white, calcareous, both persisting below to form a distinct cup; capillitium lax, the nodes white, large, angular; columella none; hypothallus none; spores distinctly rough, dark brown with the usual purple shadow, 10-12 mu. A very distinct little species related, no doubt, to _P. contextum_, but different in habit. It is never crowded, shows no plasmodiocarpous tendencies, while the outer peridium is generally deciduous except at the base and falls in flakes. Collected several times in the Three Sisters Mountains of Oregon by _Professor Morton E. Peck._ 12. PHYSARUM BRUNNEOLUM (_Phillips_) _Mass._ PLATE XX., Figs. 7, 7 _a_. 1877. _Diderma brunneolum_ Phillips, _Grev._, V., p. 114. 1888. _Diderma brunneolum_ Phill., Saccardo, _Syll. Fung._, No. 1292. 1892. _Physarum brunneolum_ Phill., Massee, _Mon._, p. 280, Figs. 221-222. 1894. _Craterium pedunculatum_ Lister, _Mycetozoa_, p. 71. 1911. _Physarum brunneolum_ Mass., Lister, _Mycetozoa, 2nd ed._, p. 63, Pl. 69, Fig. _a_. Sporangia scattered or gregarious, but not crowded, sessile, globose or sub-depressed; peridium double, thick, smooth or polished, yellow brown, stellately dehiscent, the segments reflexed, white within; columella none; capillitium dense, with nodes numerous, large irregular, internodes thin and short; spores globose, lilac, minutely warted, 6-7 mu.