This form was first described in _Grevillea_, V., p. 114, as _Diderma brunneolum_ Phillips. Later, students of the specimens preserved by Mr. Phillips, concur that we have to do not with a diderma, but with a craterium, Lister, or physarum, Massee. There seems no reason why we should not respect the decision of Massee, whose description is here quoted in form somewhat abridged. The peridium is about as double as in the many physarums, not more so; the inner membrane so delicate as only occasionally to be revealed except to scrutiny most searching. But the appearance as a whole is as of some brown diderma; only the calcareous capillitium abides to prevent mistaken reference. When opened by irregular dehiscence from above, the persisting cup-like base of the sporangium recalls _Leocarpus fragilis_; but then again the capillitium is different. California, Portugal; Colorado,--_Sturgis._ 13. PHYSARUM CINEREUM (_Batsch_) _Pers._ PLATE IX., Figs. 4, 4 _a_, 4 _b_. 1786. _Lycoperdon cinereum_ Batsch, _Elench. Fung._, p. 249, Fig. 169. 1801. _Physarum griseum_ Link, _Diss._, I, p. 27. 1805. _Physarum cinereum_ Persoon, _Synopsis_, p. 170. 1829. _Didymium cinereum_ Batsch, Fries, _Syst. Myc._, III., p. 126. 1829. _Physarum plumbeum_ Fries, _Syst. Myc._, III., p. 142. 1875. _Physarum cinereum_ Batsch, Rost., _Mon._, p. 102, in part. 1896. _Physarum plumbeum_ Fr., Morgan, _Myx. Mi. Val._, p. 98. 1899. _Physarum plumbeum_ Fr., Macbr., _N. A. S._, p. 35. 1909. _Physarum cinereum_ (Batsch) Pers., Torrend, _Flore des Myx._, p. 183. Plasmodium watery white, or transparent, wide streaming on decaying sod, etc. Sporangia sessile, closely gregarious, or even heaped, sub-globose, elongate or plasmodiocarpous, more or less calcareous, gray; peridium simple, thin, more or less densely coated with lime; capillitium strongly developed, the nodes more or less richly calcareous, the lime-knots rounded, angular; spore-mass brown, spores clear violaceous-brown, 6-7 mu, distinctly warted. This delicate, inconspicuous species is well defined by the characters given. It occurs not rarely on richly manured ground, in meadows, lawns, or even on the open prairie. The plasmodium may form rings several inches in diameter, scattered here and there over a surface several square feet in extent, in fruit ascending the blades of grass, completely covering these with the crowded sporangia. The color of the fruit is well described in the specific name; gray or ashen gray. The spores are very distinctly papillate; in some specimens, however, almost smooth; in few instances, rough. Common. New England west to the Black Hills and Pacific coast. Cosmopolitan.