Sporangia scattered or gregarious, very small, .2 mm. in diameter, violet tinted, erect, stipitate short, about one-half the total height, concolorous, slender, tapering upward; calyculus crateriform, persistent, or marked with minute plasmodic granules; the net rudimentary or poorly developed, the meshes large, irregular, the nodules also large triangular, violaceous; spores pale violet in mass, by transmitted light reddish, 7-8 mu, minutely warted. A very minute but well-marked species discovered by Dr. Rex in Wissahickon Park, near Philadelphia, otherwise very rare. Lister, however, reports it from England. In minuteness to be compared with _C. minutissima_, from which its color instantly distinguishes it. Dr. Rex reports the plasmodium as "violet black." All our specimens are on very rotten wood, basswood, _Tilia americana_. Pennsylvania, Illinois, Iowa. 13. CRIBRARIA PURPUREA _Schrad._ 1797. _Cribraria purpurea_ Schrad., _Nov. Gen. Pl._, p. 8. Sporangia gregarious, large, 1 mm. in diameter, dark purple, erect, stipitate, depressed-globose; stipe concolorous, furrowed, about twice the diameter of the sporangium in length, with a distinct hypothallus; calyculus persistent, less than half the sporangium, obscurely ribbed, marked by concentric plications, the margin toothed; the net poorly differentiated, the meshes irregular in form and size, as are also the flat, unthickened nodes, the threads pale, free ends short and not numerous; spore-mass purple; spores by transmitted light, pale or colorless, 5-6 mu, smooth. Rare. Found on rotten coniferous wood in deep forests. Easily recognized by its large size and uniform purple color. To the next species it offers a general resemblance, but has larger sporangia and an entirely different net. The plasmodium just before the formation of the fruit is scarlet. Maine, New York, Pennsylvania, Ontario, Oregon, Colorado. 14. CRIBRARIA ELEGANS _Berk. & C._ 1873. _Cribraria elegans_ Berk. & Curt., _Grev._, II., p. 67. Sporangia gregarious, erect or nodding, small, .4-.5 mm., bright purple, stipitate; stipe long, slender, tapering upward, almost black, arising from a scanty hypothallus; calyculus about half the sporangium, finely ribbed, covered especially above with small purple granules, the margin toothed or perforate; net well developed, the meshes small, polygonal, the threads delicate, colorless, with many free ends, the nodules dark-colored, numerous and somewhat prominent; spore-mass pale purple; spores by transmitted light pale violaceous, smooth, 6-6.5 mu. To be compared with the preceding. The small-meshed net with well-defined, dark-colored nodules is distinctive, aside from the fact of the much smaller sporangia. The stipe is also different, more slender, smooth, and dark-colored. The habitat of the two species appears to be the same. The present species is much more common, ranges farther west, and is to be looked for on the Pacific coast.