Distinguished from _Lamproderma_ by the peculiar manner in which the peridium is ruptured, and by the simplicity of the scanty capillitium. So far there appears to be but a single species. 1. CLASTODERMA DEBARYANUM _Blytt._ PLATE XIII., Fig. 6, and PLATE XVI., Fig. 13. 1880. _Clastoderma debaryanum_ Blytt, _Bot. Zeit._, XXXVIII., p. 343. 1886. _Orthotrichia microcephala_ Wing., _Jour. Myc._, II., p. 126. Sporangia scattered or gregarious, very minute, 1-12 to 1/4 mm. in diameter, the peridium fugacious, except the minute patches that adhere to the capillitial branchlets, and the slight annulus at the base of the columella; stipe long, unequal, dark below, above paler; columella almost none, giving early rise to the comparatively few slender threads which by their repeated forking make up the capillitium; spores globose, even, violaceous, 8-9 mu. Reported in the United States so far from Maine, Pennsylvania, Ohio, and Illinois. The sporangia are very small, but beautiful, delicate little structures, found on the bark of living red oak in this country; in Norway it seems to have been seen first on a dead polyporus. Its minuteness doubtless causes it to be generally overlooked, _N. A. F._, 2498. =3. Lamproderma= _Rostafinski_ 1873. _Lamproderma_ Rostafinski, _Versuch_, p. 7. Sporangia stipitate, globose, or ellipsoid; columella cylindric or inflated or clavate at the apex, scarcely attaining half the height of the peridium; peridium shining with metallic tints, deciduous, except where, at the base of the columella, it forms a ring around the stipe; capillitium rising in tufts or by simple branches from the columella, the threads regularly forked, generally united into a net. The lamprodermas are distinguished from the comatrichas, to which they are most nearly allied, by the arrangement of the capillitium, its development from the apex only of the columella, the continuation of the stipe within the peridium. In other words, the peridium leaves the stipe some distance below the point where the lowest capillitial branches take origin. In mature specimens the peridium has often entirely disappeared, its only trace, a collar, more or less distinct, around the stipe, marking the beginning of the columella. Nevertheless the peridium is far more persistent than in any comatricha, and shows in yet greater brilliancy the wondrous metallic tints and iridescence of _Comatricha_ and _Diachaea_. Older authors, so far as can be seen, distributed the species between _Physarum_ and _Stemonitis_. =Key to the Species of Lamproderma= _A._ Peridium metallic blue. _a._ Stipe short, stout. 1. Capillitium tips colorless 5. _L. violaceum_ _b._ Stipe long, slender. 1. Capillitium of dark, tapering, oft-united threads 3. _L. columbinum_ 2. Capillitial threads rigid, dark brown, seldom united 4. _L. scintillans_