1805. _Physarum aurantiacum_ var. _rufipes_ Alb. & Schw., _Consp. Fung._, p. 94. 1829. _Diderma rufipes_ (Alb. & Schw.) Fries, _Syst. Myc._, III., p. 101. 1873. _Physarum pulcherripes_ Peck., _Bull. Buff. Soc. Nat. Hist._, I., p. 64. 1873. _Didymium erythrinum_ Berk., _Grev._, II., p. 52. 1873. _Didymium ravenelii_ Berk. & C., _Grev._, II., p. 53. 1873. _Physarum petersii_ Berk. & C., _Grev._, II., p. 66. 1875. _Physarum schumacheri_ Spr. var. _rufipes_ Alb. & Schw., Rost., _Mon._, p. 99. 1894. _Physarum pulcherripes_ (Peck), Lister, _Mycetozoa_, p. 41. 1896. _Cytidium rufipes_ (Alb. & Schw.) Morg., _Jour. Cin. Soc. Nat. Hist._, p. 81. 1899. _Physarum rufipes_ (Alb. & Schw.) Morg., Macbr., _N. A. S._, p. 50. 1911. _Physarum pulcherripes_ Peck., List., _Mycetozoa, 2nd ed._, p. 49. Sporangia gregarious, dark-colored, sprinkled with orange flakes of lime, globose, the wall thin, deciduous, stipitate; stipe slender, erect, deep red, sometimes black below, pale or orange above, and supported on a well-developed hypothallus; columella scant or none; capillitium dense, the meshes and nodes unusually small and delicate, the latter reddish or yellow; spore-mass black; spores by transmitted light, violet-tinted, 8-10 mu., almost smooth. The striking contrast of color between sporangia and stipes renders this species at sight, quite distinct from any related form. The peridia in the specimens before us are black or iridescent-black sprinkled more or less profusely with orange lime granules which sometimes cover all but the base. The stipe, springing from a small hypothallus, is dark red below for about one-fourth its height, then vermillion, above expanding slightly beneath the peridium; the columella scant or none. The capillitium is an elegant delicate net, with numerous small, uniformly regular, calcareous nodes, orange; by transmitted light, yellow. The spores, brown in mass, are, by transmitted light, pale violet, slightly papillose, 8-10, mostly about 8 mu. The plasmodium is probably yellow. This species is no doubt related to _P. psittacinum_. It is, however, much smaller, has a calcareous stipe, and a much less variegated peridium, and generally a small columella. It is also akin to _P. globuliferum_ and to _P. murinum_, _P. petersii_ Berk. & C. is reported the same thing. 26. PHYSARUM PENETRALE _Rex._ PLATE XV., Figs. 6, 6 _a_. 1891. _Physarum penetrale_ Rex., _Proc. Phil. Acad._, p. 389. 1899. _Physarum penetrale_ Rex., Macbr., _N. A. S._, p. 55. 1911. _Physarum penetrale_ Rex., List., _Mycetozoa, 2nd ed._, p. 36.