1831. _Enteridium cinereum_ Schw., _N. A. F._, No. 2365. 1875. _Physarum ellipsosporum_ Rost., _Mon. App._, p. 10. 1884. _Aethaliopsis stercoriformis_ Zopf., _Pilzthiere_, p. 150. 1894. _Fuligo ellipsospora_ Lister, _Mycetozoa_, p. 67. 1896. _Fuligo cinerea_ (Schw.) Morg., _Cin. Soc. Nat. Hist._, p. 105. 1899. _Physarum ellipsosporum_ Rost., Macbr. _N. A. S._, p. 27. 1911. _Fuligo cinerea_ Morg., List., _Mycetozoa_, 2nd ed., p. 88. Plasmodium milk-white, watery. Plasmodiocarp long and widely effused, anon winding, here and there reticulate, always applanate; sometimes in form an aethalium, the peridial cortex membranous, firm, thick, and white. Capillitium well-developed, furnished with lime. Spores thin-walled, ellipsoidal, violaceous, plicate-rugose, 14-16 x 11-12 mu. Not common. Found occasionally in shaded situations on piles of rotting straw or in the woods, especially on detritus of the bracken. The spores are many of them ellipsoidal; some are spherical; all are decidedly spinulose, perhaps might appear plicate-rugulose when dry or shrunken. Calcareous nodules very large and irregular, white. Schweinitz, _loc. cit._, described this form as _Enteridium cinereum_. Rostafinski referred it to the genus _Physarum_, but was obliged to adopt also a new specific name, as that suggested by Schweinitz was already in use in the genus _Physarum_. Zopf, _Die Pilzthiere_, p. 149, founds a new genus on what seems to be the same form as here considered. This he publishes as _Aethaliopsis stercoriformis_ Z. Massee regards the specimens discovered by Zopf as belonging to the genus _Fuligo_, and Lister regards Rostafinski's type as _Fuligo_, and includes Zopf's material under the Rostafinskian species. This has been described as properly an American form; Lister cites other far localities. 3. FULIGO SEPTICA (_Linn._) _Gmel_. 1753. _Mucor septicus_ Linn., _Sp. Pl._ II., No. 1656 (?). 1763. _Mucor ovatus_ Schaeff., _Fung. Bav._, p. 132, Fig. 192. 1791. _Fuligo septica_ (Linn.) Gmel., _Syst. Nat._, p. 1466. 1826. _Fuligo varians_ Sommf., _Fl. Lapl. Sup._, p. 231. 1809. _Aethalium flavum_ Link, _Diss._, I., p. 42. 1829. _Aethalium septicum_ Fr., _Syst. Myc._, III., p. 93. 1875. _Fuligo varians_ Sommf., Rost., _Mon._, p. 134. 1892. _Fuligo varians_ Sommf., Macbr., _Bull. Lab. Nat. Hist. Ia._ II., p. 160. 1894. _Fuligo septica_ (Linn.) Lister, _Mycetozoa_, p. 66. 1899. _Fuligo ovata_ (Schaeff.) Macbr., _N. A. S._, p. 23. 1911. _Fuligo septica_ Gmel., Lister, _Mycetozoa, 2nd ed._, p. 86. This remarkable and universal species presents as stated many forms and phases. Of these five have been selected as representative. 1. Form _a._ Plasmodium yellow; cortex yellow, or orange-brown, strongly calcareous friable; form indefinite _F. ovata_