A very well marked species, easily recognized, at least when stipitate, by its remarkable discoid or lenticular sporangia. After the spore-dispersal, the stipes are long-persistent, surmounted by a peculiar disk representing the consolidated columella, lower sporangial wall, and expanded stem-top. Sessile specimens are like similar forms of _D. reticulatum_, but in all the gatherings before us the stipitate type is at hand to reveal the identity of the species. Rostafinski's figures, 131, 146, 149, and 150, adapted from Corda, exaggerate the hypothallus, but otherwise leave nothing to be desired. As to synonymy, Bulliard has plainly the priority. His figure, t. 446, Fig. 1, can refer to nothing else, especially reenforced as it is by Sowerby, _Eng. Fung._, t. 12. Rather rare on fallen stems of herbaceous plants, but widely distributed, New England to Oregon and Washington. 11. DIDERMA SAUTERI (_Rost._) _Macbr._ 1875. _Chondrioderma sauteri_ Rost., _Mon._, p. 181. 1891. _Chondrioderma aculeatum_ Rex, _Proc. Phil. Acad._, p. 390. Sporangia scattered, gregarious, sessile, lenticular or hemispherical, flattened above and sometimes concave or umbilicate below, dusky or yellowish white, the outer peridium papyraceous, thin, occasionally wrinkled, rupturing irregularly, remote from the inner, which is thin, delicate, semi-transparent, grayish, rarely iridescent; hypothallus none; columella irregular, sometimes small and hardly evident, rugose, with spine-like processes, the persisting bases of the capillitial threads, reddish brown; capillitium scanty, white, or colorless, simple or sparingly branched; spores dark violaceous, spinulose, 12-13 mu. This is _Chondrioderma aculeatum_ Rex, _Proc. Acad. Nat. Sci. Phil._, 1891, p. 390. After careful comparison of specimens and various descriptions, especially that of Rostafinski with the type specimens of Dr. Rex, I am constrained to concur with Lister in adopting Rostafinski's name. The sporangia in the type specimens (Rex) are on moss, borne at the extreme tips of acuminate or aculeate leaves, so that at first sight they appear stipitate. Apparently rare. Maine, New York. 12. DIDERMA COR-RUBRUM _Macbr. n. s._ PLATE XVIII., Fig. 2 Sporangia gregarious clustered, small .5-.7 mm., sessile corrugate-plicate, especially above, snow-white, the outer peridium cartilaginous polished without and within, the inner delicate, evanescent; columella well developed, globose or clavate, anchored by several stout transverse trabeculae to the peridial wall, papillate, deep-red as is the peridium especially below; capillitium very delicate, sparingly branching, colorless; spores verruculose, fuliginous tinged with red, about 12 mu.