This extremely delicate and beautiful form is certainly not to be referred to _Tilmadoche alba_ (Bull.) Fr. Fries, who seems to have known of _P. compressum_ A. & S. and refers _it_ to _P. nutans_ Pers., _op. cit._, p. 130, annotates the present species: "Species especially remarkable in the stipe, in the internal structure, and in its whole habit, nor is there any other with which it may be compared. Peridium thin, not uniform, presently breaking up into laciniate scales; at first yellow, then bluish-ashen; when empty, white. The form inconstant, globose, depressed, but never umbilicate at the base." If we may judge by what Fries says on the subject, he certainly distinguished clearly between this species and _T. alba_ (Bull.), to say nothing of the stouter, larger, in every way coarser forms called by Rostafinski _P. nefroideum_, _P. compressum_, _P. lividum_, etc. The shadowy little species has had an eventful history, dipping in and out of our story in most uncertain fashion. Beginning with Fries, as noted, it received confirmation at the hands of DeBary, and by Rostafinski was given priority over a long list of synonyms, and figured. The earlier English authors follow Rostafinski, but for Lister in the _Mycetozoa_, p. 51, the species becomes a synonym of _T. alba_ as _P. nutans_, the description appropriately enlarged to receive it. Meantime American students generally confused it with the tilmadoches on the one hand and _P. nefroideum_ R. (supposed) on the other. In 1897, Robt. Fries in _Sver. Myxom. Flora_, brings the species again to view as co-partner with _P. nutans_ and in the _Mycetozoa, 2nd ed._, p. 67, it appears as sub-species to the same. The resemblance to _P. album_ or _P. nutans_, is chiefly as intimated, a matter of definition; real differences are found in the irregular capillitium, fitting a globose sporange, in the character of the stipe and the consequent pose. See under _P. nutans_ and _P. notabile_. 34. PHYSARUM NODULOSUM _Cke. & Balf._ 1881. _Physarum nodulosum_ Cke. & Balf., _Rav. N. A. F._, Exsic., 479. 1889. _Badhamia nodulosa_ Massee, _Jour. Myc._, Vol. V., p. 186. 1891. _Physarum calidris_ Lister, _Jour. Bot._, Vol. XXIX., p. 258. 1896. _Craterium nodulosum_ (Cke. & Balf.) Morg., _Jour. Cin. Soc._, p. 87. 1899. _Physarum nodulosum_ Cke. & Balf., Macbr., _N. A. S._, p. 51. 1911. _Physarum pusillum_ List., _Mycetozoa, 2nd ed._, p. 64. Sporangia gregarious; minute, globose, bluish-white, the sporangial wall thin and more or less encrusted with lime, breaking up irregularly, stipitate; stipe slender, longer than the sporangium, attenuate upward or even, bright brown, rugose, expanded above into a shallow cup-like base for the sporangium; columella none; capillitium with lime-knots more or less abundant, white, often uniting, badhamioid; spore-mass black; spores by transmitted light, pale lilac-brown, almost smooth, 10-12 mu. Pennsylvania, Ohio, Iowa; Canada.