Sporangia sessile, crowded or heaped in small bunches, a dozen or more sporangia in one pile, spherical, ovoid or elongate, yellow or greenish yellow; peridium thin, fragile; capillitium delicate, with rather small, irregular, yellowish, calcareous nodes; columella none; spores bright violet, minutely roughened, 7-9 mu. This species occurs more commonly on moss-tufts, with which it is frequently con-colorless, or escaped on dead leaves, etc. The peridium is flecked with calcareous scales or grains stained yellow or green, and to these the whole fruit owes its peculiar color. The color and aggregate, heaped sporangia are distinctive macroscopic characters. In the _Monograph_, p. 113, Rostafinski adopted properly Ditmar's name for this species. Upon later consideration, in the _Appendix_, p. 8, he changed the name, writing _P. ditmari_, on the ground that _virescens_ was descriptive of a character to which the species in question occasionally refuses to conform. Most authors since Rostafinski have simply accepted his suggestion, so that the species is often entered _P. ditmari_ Rost. _P. virescens_ is certainly to be preferred. _N. A. F._, 2692. Canada, New England, New York, Pennsylvania, Ohio, Iowa, Black Hills, South Dakota. 15. PHYSARUM RUBIGINOSUM _Fries_. 1817. _Physarum rubiginosum_ Fries, _Symb. Gast._, p. 21. Plasmodium scarlet. Sporangia globose or cylindric, sessile or sometimes narrowed to a stem-like base as if short-stipitate, olivaceous brown with sometimes a flush of red; the peridium simple, thin rugulose or plain, the calcareous scales few, or apparently included; columella none; capillitium dense, the nodules rather large, angular, rusty brown; spores dull violaceous, gently roughened, about 10 mu. A beautiful well-marked species, but evidently rare in North America. Our only typical specimens are from the gatherings by Mr. Wingate, part of which is by Lister referred to this species, _Mycetozoa, 2nd ed._, p. 82. _P. rubiginosum_ Fr. in the _N. A. S._, 1899, is based on certain west coast specimens now known as _Badhamia decipiens_ Berk. In Colorado there occurs a plasmodiocarpous form of the species. It has the characteristic spore and capillitium but in form and habit differs very decidedly. The fructification is a delicate netted plasmodiocarp, the tubule about .5 mm., bright red; the peridium simple, cartilaginous, dehiscent from above, and flecked with just here and there a red calcareous scale. Collected at Palmer Lake; _Professor Bethel._ 16. PHYSARUM INSTRATUM _Macbr. n. s._ 1899. _Physarum thejoteum_ Macbride, _N. A. S._, p. 36, not Fries, as cited. 1911. _Physarum virescens_ Ditmar, Lister, _Mycetozoa, 2nd ed._, p. 83.