268 THE MYXOMYCETES 



tion 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. 1, pi. 5, figs. 4, 5). 

 Batsch simply named and described Micheli's figure, 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. The capillitium is coarser and 

 rougher than in A. denudata and does not decolorize so readily in 

 potassium hydroxide solution. 



Var. fulgens Lister, Mycetozoa ed. 2. 242, 1911, is said to be dis- 

 tinguished by crimson sporangia and firm dark stalks. As both color 

 and stipe are variable this variety seems to be of slight value. 



Var. laxa Brandza, Bull. Soc. Myc. Fr. 44 : 283, 1929, with large 

 sporangia, 2-3 mm. tall, becoming 3-4 mm. when the lax capillitium 

 is fully expanded, is recorded from Rumania and Switzerland. 



Common in the eastern and central portions of the United States 

 and Canada and generally distributed in temperate regions, also the 

 Virgin Islands; Java, Malay Peninsula, South and East Africa. 



7. Arcyria nodulosa Macbr. 



N. A. Slime-Moulds ed. 2. 252. 1922. 

 1899. Arcyria incarnata Pers. var. nodulosa Macbr., N. A. Slime-Moulds 194. 



Sporangia small, about 1 mm. high when unexpanded, crowded in 

 clusters of varying size, dull red or brownish, stipitate; 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 \x wide, 

 expanded in globose, spinulose, or papillate-reticulate nodules, es- 

 pecially 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 (jl. 



This species is not distantly related to A. incarnata, 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 and 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. 



Pennsylvania. 



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