The Myxomycetes of Eastern Iowa. 145 



distinguishable from any frothy substance of accidental occur- 

 rence. Presently the whole mass undergoes internal trans- 

 formation, [inor-phosis^ Fries), and becomes a mass of blue- 

 black, bur-like spores, covered with a dry fragile rugose 

 cortex, which is but slowly disintegrated by wind and rain. 

 The Fig. 6b hardly represents the stout, pale fuscous strands 

 of the capillitium. 



IX. DIDYMIACEiE. 



Sporangia simple, single or plasmodiocarpous. Peridium 

 simple and calcareous or double, when the outer wall only is 

 calcareous. Columella short, hemispherical or wanting. Capil- 

 litium of thin colorless or purplish threads radiating from the 

 columella or base of the fructification to the peridium, gener- 

 ally without lime. Spores violet-black. 



KEY TO THE GENERA. 



Peridial lime deposits, crystalline, Didymium. 



Peridial lime deposits, amorphous granules, . Chondrioderma. 



DIDYMIUM, Schrader. 



Sporangia distinct or plasmodiocarpous; peridium simple or 

 double, the outer wall covered usually with calcareous scales, 

 sometimes united to form a crust. Columella, the enlarged 

 head of the stipe or w^anting. Capillitium lime-free, delicate. 



A large genus distributed throughout the world but repre- 

 sented in Iowa so far by but three species. 



43. Didymium proximum, Berkeley and Cooke. Plate X, 

 Figs. 4, 4« and ^b. 



Sporangium nodding, globose farinaceous; the stipe attenu- 

 ate upwards, luteous. Columella none; flocci pale, few. 

 Spores pale violet, smooth, .007-.009. 



