In The _Journal of Botany_, 52, p. 100, the distinguished author and artist records the discovery of this species in the mountains of Switzerland. She says: "This specimen shows a striking resemblance to _Leocarpus fragilis_ Rost., both in the shape of the sporangia and in the capillitium and spores; but although the color of the sporangia varies in both these species, the walls of _P. (L.) fulvum_ are membranous and rugose with included deposits of lime granules and show nothing of the polished cartilaginous layers characteristic of _L. fragilis_." The species is a boundary type at best, and shows again how artificial all our taxonomy is apt to prove, when the number of presentations of some particular type becomes larger. For these reasons, the present author writes _Physarum_, and believes the question of identity in a perplexing case fortunately settled. 46. PHYSARUM VARIABILE Rex. 1893. _Physarum variabile_ Rex, _Proc. Phil. Acad._, p. 371. 1911. _Physarum variabile_ Rex, List., _Mycetozoa, 2nd ed._, p. 47. Sporangia scattered, stipitate, sub-stipitate or sessile, about 1 mm. high; regularly or irregularly globose, ellipsoidal, obovate or cylindric-clavate in shape; sporangium wall sometimes apparently thick, of a dingy yellow or brownish-ochre color, slightly rugulose on the surface, crustaceous, brittle, rupturing irregularly, sometimes thin, translucent, covered externally with flat circular calcic-masses falling away in patches; stipes nearly equal, occasionally much expanded at the base, rough, longitudinally rugose, variable in size, sometimes one-third of a millimetre high, sometimes a mere plasmodic thickening of the base of the sporangium; color of stipes varying from a yellowish-white to a dull brownish-gray; capillitium a small-meshed network of delicate colorless tubules with large, many-angled, rounded masses of white, or rarely yellowish-white lime-granules at the nodes; no true columella, but often a central irregular mass of white lime-granules; spores dark violet-brown, verruculose, 9-10 mu. Pennsylvania. _Dr. Rex._ Lister, _op. cit._, describes a variety, _sessile_, presenting plasmodiocarpous fructification, from Ceylon, also from Antigua, but there are some doubts as to the identity of these with American sessile and plasmodiocarpous forms. Vid. _Jour. Bot._ XXXVI., p. 113. 47. PHYSARUM AURISCALPIUM _Cooke_. 1877. _Physarum auriscalpium_ Cooke, _Myx. U. S._, Am. Lyc. Nat. Hist. N. Y., XI., p. 384. 1877. _Physarum auriscalpium_ Cke., _Myx. Gr. Brit._, Pl. 24, f. 253-4. 1893. _Physarum sulphureum_ (Alb. & Schw.), Sturgis, _Bot. Gaz._, XVIII., p. 197. 1898. _Physarum auriscalpium_ Cke., List., _Jour. Bot._, XXXVI., p. 115. 1911. _Physarum auriscalpium_ Cke., List., _Mycetozoa, 2nd ed._, Syn. excl.