252 THE NORTH AMERICAN SLIME-MOULDS 



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 Per- 

 soon, and is well shown in his figure {Obs. Myc. I., p. 58, pi. V. 

 Figs. 4 and 5) referred to by Gmelin, /. 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 Mex- 

 ico. 



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 perid- 

 ium 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 fx 

 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 dis- 

 tinctly roughened, globose, 10—12 /x. 



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 col- 

 or with longer stipes, larger, rougher spores; the capillitium is also 

 peculiar, the threads unusually wide and densely corrugated trans- 

 versely, 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. 



