Plasmodium in rotten wood, white or nearly transparent; when fruiting, forming on the substratum mould-like patches composed of the minute sporiferous pillars, generally in clusters of three or more together; spores white, ovoid, or ellipsoidal, smooth, 10-12x6 mu. Very common, occurring in summer on shaded rotten logs, especially after warm showers and in sultry weather. Easily distinguishable from all similar moulds by the absence of mycelium or of anything like a hypha. In Europe the plant seems to be in autumn exceedingly common. Micheli not only described the form but figured it, nearly two hundred years ago. Micheli's figure is good, as is that of Mueller, _Fl. Dan._, l. c. Mueller referred the species to a Linnean genus _Byssus_, which seems to have included Algae rather than anything else, if one can determine its limits at all. The same thing is true of _Tremella_; but this name is now otherwise applied, as are all the other generic names down to _Ceratium_, Alb. & Schw. But this had been by Schrank preoccupied, 1793. See the reference above for 1889. As for specific name, there seems no reason to depart from the rule of priority, since Mueller's work is determinative. _Ceratiomyxa arbuscula_, Berk. & Br., apparently a form of this, is cited from Toronto by Miss Currie. Massee gives it recognition; Lister as varietal. The sporophores are inclined to be simple, stipitate and dendroid. _C. filiforme_ of the English authors latest named is a wonderful thing and deserves a paragraph here, if not recognition as a distinct species. It occurs rarely; but once it appears, attracts attention. As in the historic species, the sporifers are white, stand more or less erect, but are every way finer and larger. Each individual sporifer rises like a stiff stem, as of white thread, 2-3 mm. high; at top a tuft of fruiting branchlets, more or less distinct. All taken together, we have a dense mat completely concealing the substratum and spreading out sometimes over an area of surprising extent, several centimetres square. Common everywhere in summer on decaying sticks and wood of every description, especially in wet places. Alaska to Nicaragua, and probably around the world. 2. CERATIOMYXA PORIOIDES (_Alb. & Schw._) _Schroeter._ 1805. _Ceratium porioides_ Alb. & Schw., _Consp. Fung._, p. 359. 1829. _Ceratium porioides_ Fries, _Syst. Myc._, III., p. 295. 1873. _Ceratium porioides_ Fam. & Wor. _Acad. Imp._, XX., 3, p. 5. 1889. _Ceratiomyxa porioides_ Schroet., _Engl. u. Prantl_, I., i., p. 16. 1894. _Ceratiomyxa mucida_ Schroet. var. _porioides_ Lister, _Mycetozoa_, p. 26. 1899. _Ceratiomyxa porioides_ Alb. & Schw. (Schroet.), Macbr., _N. A. S._, p. 19. 1911. _Ceratiomyxa porioides_ Alb. & Schw., Schroet., _List. Mycet._, p. 26, _var._