The present species well illustrates the difficulty confronting the author of to-day who, discussing a group of microscopic organisms, would fain use the nomenclature of his predecessors, honored, but equipped with insufficient lenses. Here is a species reported common in Europe, observed by every mycologist there, from Micheli down, and yet awaiting adequate description until Rostafinski in his great book, gives the results of microscopic analysis. We are now really dealing with _P. cinereum_ Rost; _P. cinereum_ Batsch is a compliment to certain rather clever water-color drawings. Rostafinski gives a long list of synonyms, none, it is believed, represent American forms; and without taking careful thought, surely no one would rudely disturb such honorable interment; but, in his description the range of spore-measurement, 7-13.3 mu, gives us pause, and raises the suspicion that possibly, in one case or another, the sepulture were perhaps premature. The range is too great! Perhaps, in the series offered in confirmation, small-spored forms represent one species, large-spored, something else? European students may decide this at their leisure. But Rostafinski having, not without much labor, practically completed his review of the physaroid forms had almost finished the last genus _Badhamia_, when his mind perhaps returned, no doubt with some lingering misgivings, to the thirteenth species in his physarum list. There were there, he recalled, some large-spored specimens which had rather badhamioid capillitium. The sessile physarums of Fries were also before him, those especially, "floccis albis." Of these one shall be _B. panicea_, one _B. lilacina_ and one _B. verna_, described as having rather delicate colorless capillitial tubes combined in a loose net, the calcareous deposits about the enlarged intersections scanty, the spores 12.5 mu. The description of the fructification as a whole is a condensed statement of that which describes _P. vernum_, and all taken together indicates some physarum. See now No. 3 preceding, p. 51. _P. plumbeum_ Fr. belongs here. It has similar spores, the only difference is a less calcareous peridium and more scattered habit of fructification with more nearly regular, depressed-globose sporangia. _P. cinereum_ Pers. as cited by Link, _op. cit._, is apparently a badhamia, may be _P. vernum_, while P. _griseum_ is probably the present species. 14. PHYSARUM VIRESCENS _Ditmar_. PLATE VIII., Figs. 7, 7 _a_, 7 _b_. 1817. _Physarum virescens_ Ditmar, Sturm, _Deutsch. Fl. Pilze_, I., p. 123, Pl. 61. 1875. _Physarum ditmari_ Rost., _Mon., App._, p. 8. 1892. _Physarum ditmari_ Rost., Macbr., _Bull. Lab. Nat. Hist. 1a._, II., p. 155. 1894. _Physarum virescens_ Ditmar, Lister, _Mycetozoa_, p. 65. 1909. _Physarum virescens_ Ditmar, Torrend, _Flo. d Myx._, No. 207. 1911. _Physarum virescens_ Ditmar, Lister, _Mycetozoa, 2nd ed._, p. 83.