NOTE.--Each figure exhibits the sporangium as it appears magnified about 100 diameters, and the capillitium and spores magnified about 500 diameters. [Illustration: The Journal of the Cin. Soc. Natural History. VOL. XVI. PLATE I.] * * * * * THE MYXOMYCETES OF THE MIAMI VALLEY, OHIO. BY A. P. MORGAN. Third Paper. (Read February 6, 1894.) ORDER VI. STEMONITACEÆ. Sporangia globose or ovoid to oblong and cylindrical, stipitate; the wall very thin and fragile, soon disappearing. Stipe tapering upward and continued within the sporangium as a more or less elongated columella. Capillitium of slender brown threads, arising from numerous points of the columella, repeatedly branching and usually anastomosing to form a network, persistent and rigidly preserving the outline of the sporangium. Spores globose, brown or violaceous. This order is readily distinguished by the brown persistent capillitium, arising from a lengthened columella, and rigidly maintaining the form of the sporangium. Table of Genera of Stemonitaceæ. _A. Stipe and columella brown or black._ _a. The columella scarcely reaching the center of the sporangium._ 1. CLASTODERMA. Threads of the capillitium forking several times, but not combined into a network. 2. LAMPRODERMA. Threads of the capillitium branching and anastomosing to form a network. _b. The columella extending beyond the center of the sporangium._ 3. COMATRICHA. Threads of the capillitium forming only an interior network, attaining the wall by numerous more or less elongated free extremities. 4. STEMONITIS. Threads of the capillitium forming an interior network of large meshes and a superficial network of smaller meshes. 5. ENERTHENEMA. Threads of the capillitium pendent from a discoid membrane at the apex of the columella. _B. Stipe and columella white or yellowish._ 6. DIACHAEA. Threads of the capillitium branching and anastomosing to form a network. I. CLASTODERMA, Blytt. Sporangium regular, globose, stipitate; the wall very thin and fragile. Stipe elongated, tapering upward, entering the sporangium as a very short or nearly obsolete columella. Capillitium arising by a few branches from the apex of the columella, these branches forking several times at a sharp angle, but not combined into a network, the ultimate branchlets long and free, or only connected together at their tips by persistent fragments of the sporangial wall. Spores globose, violaceous. The claim of this genus to be distinguished from Lamproderma must rest upon the fact that the branchlets of the capillitium do not anastomose and form a network. It is the same as the genus Orthotricha of Wingate.