Sporangia closely crowded, cylindric, 1–1.5 mm. high, rosy or flesh-colored, stipitate or almost sessile; stipe generally short, sometimes barely a conical point beneath the calyculus; hypothallus none; peridium wholly evanescent, except the shallow, saucer-like, inwardly roughened calyculus; capillitium loose, broad, pale reddish, attached to the cup at the centre only by strands which enter the hollow stem, the threads adorned with transverse plates, cogs, ridges, etc., arranged in an open spiral; spore-mass rosy, spores by transmitted light colorless, nearly smooth, 7–8 µ.

This common species is well marked both by its color and by the delicate attachment of the capillitium to the calyculus. This is so frail that the slightest breath ofttimes suffices to effect a separation, and the empty calyculi are not infrequently the only evidence of the fructification. This peculiarity did not escape the attention of Persoon, and is well shown in his figure (Obs. Myc., I., p. 58, pl. V. Figs. 4 and 5) referred to by Gmelin, l. c. Batsch simply named and described Micheli's figure (Tab. XCIV., Fig. 2), and accordingly his claim to priority is no better than Micheli's figure, which may possibly concern the present species, but is in no sense determinative. It is impossible to say what Retzius meant by his Clathrus ramosus, cited by Fries as a synonym here.

Common, especially in the Mississippi valley and south; more rare in the west; Black Hills, South Dakota; Toronto to New Mexico.

6. Arcyria nodulosa Macbr.

[Plate III]., Fig. 8.

Sporangia small, about 1 mm. high when unexpanded, crowded in clusters of varying size, dull red or brownish, stipitate; the peridium evanescent except the cup; stipe very short, concolorous, plicate as the cup, or both smooth and unmarked; capillitium centrally attached, slowly expanded, open-meshed, dense, the threads even, 5–6 µ wide, expanded in globose, spinulose, or papillate-reticulate nodules, especially at points of intersection, marked everywhere by close-set, transverse, sharp-edged ridges, which encircle the thread and show no trace of spiral arrangement; spore-mass brown or red brown; spores by transmitted light pale yellow or colorless, minutely but distinctly roughened, globose, 10–12 µ.

This variety is not distantly related to the preceding, as shown by the centrally attached capillitial mass, but differs in several definite particulars; the sporangia are much smaller of an entirely different color with longer stipes, larger, rougher spores; the capillitium is also peculiar, the threads unusually wide and densely corrugated transversely, expanding at frequent intervals into globose nodules which are sometimes double the width of the thread. In color suggests A. affinis Rost., but corresponds to no other particular.

7. Arcyria ferruginea Sauter.

[Plate XII.], Figs. 6, 6 a, 6 b.