This species is easily recognizable by its brilliant yellow color, somewhat rugose, sometimes scaly peridium, its richly calcareous capillitium, also bright yellow where not weathered or faded, its dark brown, translucent, non-calcareous stem. In dehiscence, the base of the peridium in cup-form, sometimes persists. This circumstance, with the fact that decaying maize-stalks and leaves are a favorite habitat, led Professor Morgan to its description as _Craterium maydis_. But it is doubtless a physarum, occurring on habitats of all sorts, from Ohio to Iowa, Colorado and Washington. Ceylon(?). _Physarum ornatum_ Peck is doubtfully cited here, although Professor Morgan thought it the same as _P. oblatum_. As a matter of fact the original brief description, _op. cit._, does not suggest either _P. oblatum_ or _P. maydis_; rather a form of _Tilmadoche viridis_. Professor Sturgis, _Notes on Some Type Specimens of Myxo., in the N. Y. Museum, Trans. Conn. Acad. Arts and Sci._, Vol. X., Pt. 2, p. 470, says that of the type almost nothing remains, that the name _P. ornatum_ Pk. "should be discarded." 49. PHYSARUM GALBEUM _Wing._ 1890. _Physarum galbeum_ Wing., Ell., _N. A. F._, 2491 (no description). 1892. _Physarum petersii_ Berk. & C., Mass., _Mon._, p. 296, in part. 1894. _Physarum berkeleyi_ Rost., List., _Mycetozoa_, p. 48, in part. 1899. _Physarum galbeum_ Wing., Macbr., _N. A. S._, p. 53. 1911. _Physarum galbeum_ Wing., List., _Mycetozoa, 2nd ed._, p. 59. Sporangia scattered, globose, stipitate, often nodding, golden yellow, the peridium exceedingly thin, breaking up into patches on which the yellow lime granules are conspicuous; stipe non-calcareous, pale brown or amber-colored, longitudinally wrinkled, about one and one-half times the diameter of the peridium; columella none; hypothallus none; capillitium dense, extremely delicate, the nodes only here and there calcareous, the lime knots when present small, angular, yellow; spore-mass pale brown; spores almost smooth, lilac- or violet-tinted, 7.5-10 mu. Distinguished among the small delicate species with which it will be naturally associated, by the yellow, richly calcareous wall of the globose sporangium and the almost limeless capillitium. The stipe is hollow and contains irregular masses of refuse granular matter, but no lime so far as we have been able to discover. _P. flavicomum_, to which the species is related most closely, differs in having the wall non-calcareous, iridescent, as well as in the color throughout; the character of the capillitium, in which lime is abundant; the absence of refuse-matter in the stem. Pennsylvania, Iowa, Minnesota. 50. PHYSARUM TENERUM _Rex._