1889. _Physarum albescens_ Ellis _in litt_: not described. 1893. _Physarum auriscalpium_ Cke., Macbr., _Bull. Lab. N. H. Iowa_, No. 2, p. 155, in part. 1894. _Physarum virescens_ var. _nitens_ List., _Mycetozoa_, p. 59, in part. 1899. _Physarum virescens_ var. _nitens_ List., Macbr., _N. A. S._, p. 34, in part. 1899. _Leocarpus fulvus_ Macbr., _N. A. S._, p. 82. 1911. _Physarum fulvum_ Lister, _Mycet., 2nd ed._, p. 60. 1911. _Physarum virescens, nitens_ List., _Mycet., 2nd ed._, p. 84, in part. Sporangia gregarious, scattered, ovoid or globose, pale yellowish or fulvous, opening irregularly above, stipitate; the peridium double, the outer layer more or less calcareous, the inner delicate, almost indistinguishable, persistent below as a shallow cup; the stipe long, weak, striate, fulvous or yellow; hypothallus distinct, venulose, or more or less continuous; capillitium pallid or white, dense, with here and there below large continuous yellow calcareous nodules; columella none; spore-mass black; spores by transmitted light, dark brown, rough, 13-15 mu. Varies to forms with single (inner) peridium and simple physaroid capillitium. _Vid._ descriptions cited for _P. auriscalpium_, _P. nitens_, etc. This interesting form is from our western mountains, and suggests at first a diderma; but the capillitium is entirely unlike that of a diderma in color and structure, and plainly belongs here. Plasmodium yellow, on fallen leaves and twigs. Our material is from Prof. Bethel, Denver; and Lake Tahoe, Nevada; later from Dr. Weir, Montana. No doubt common at high altitudes near the snow-line in mountainous regions, probably around the world. As indicated above, this was originally entered as of the genus _Leocarpus_; the taxonomic history of the form may interest readers who note with surprise the presentation in synonymy here developed. About thirty-five or forty years ago Dr. Harkness of California sent to Mr. Ellis of New Jersey a slime-mould which the sender referred to _Diderma albescens_ Phillips, (_Grev._ V., p. 114, 1877). Ellis sent a small bit to the Iowa herbarium without other comment, save that he thought it a physarum. Sometime later Mr. Ellis received from Father Langlois, a correspondent in Louisiana, specimens he esteemed the same thing. He expressed the opinion that if this were what Phillips had found in California, it should perhaps be called a physarum. The Louisiana material by his courtesy came also to this table. The material was scanty, in poor condition, and all waited further light. To these specimens the writer paid less attention. They were in the hands of his correspondents and the courtesy of the case required their further consideration by Dr. Rex.