This species in the United States is one of the most variable in the whole group. The extremes of such variation might easily constitute types for several distinct species were it not that in all directions the varieties shade into each other so completely as to defy definition. We have before us specimens purple throughout and short-stemmed; purple with stem long, pale and twisted at apex; brown, with the same variations; short-stemmed, with the apex of the stem pallid, and long-stemmed, with and without the same peculiarity. Morgan (_Cin. Soc. Nat. Hist. Jour._, 1893) would set off the purple, long-stemmed forms as _D. longipes_, "stipe three to five times the sporangium," but here are forms in which the stem is ten times the diameter of the sporangium, which yet possess in all other particulars the characters of the short-stemmed forms. European forms also vary. Massee figures one type; Lister, one or two others; Rostafinski's figure indicates a taller form; Fries says, "Stipes elongatus, peridio quinquies et ultra longior." It seems reasonable to suppose that the variation is largely due to atmospheric conditions at the time of fruiting. The purple forms may be cases of arrested development, since the plasmodium appears to be in all cases purple, or at least they seem to represent those plasmodia which have failed of normal ripening. We may recognize two or three general types, distinguished primarily by color:-- a. _D. cancellatum cancellatum._--Sporangia clear brown or with only a purplish tinge, the stipe tapering upward, and in extreme cases perfectly white at the twisted apex. The stipe in length ranges from three to ten times the diameter of the sporangium. The reticulations of the net are generally small and the ribs numerous. This is the most highly differentiated, finished type of the species. b. _D. cancellatum purpureum._--Sporangium dark, the purple tints predominating, the stipe tapering upward, more or less twisted at the paler, sometimes almost colorless, apex. The stipe ranges a little shorter than in the preceding variety, three to seven times the sporangium. The reticulations of the net are often coarse, the ribs being fewer; the whole structure weak and showing signs of imperfect development. The figures, 1, 1 _a_, 1 _b_, 1 _c, l. c._, illustrate the ideal accomplishment in form (a). The color is a clear definite brown with no suggestion of purple anywhere. The stipes are three or four times the diameter of the sporangium, brown below, white above, and twisted to allow the sporangium to hang inverted. This is complete in every part; a definite bell-shaped calyx, widening into the cancellate receptacle, the margin constricted, and closed at last by the apical net, _cribrum_, sign of the order.