120 THE MYXOMYCETES 



22. Didymium trachysporum G. Lister 



Essex Naturalist 20 : 113. 1922. 



Sporangia more or less scattered, white or cream white, either 

 hemispherical, 0.2-0.6 mm. in diameter, or forming slender, curved, 

 simple or ring-shaped plasmodiocarps; the outer wall a smooth or 

 wrinkled crust of closely compacted lime granules; the inner wall 

 membranous, colorless; the floor of sporangium pale yellow, mem- 

 branous, with a thickened margin, with scanty, rarely abundant de- 

 posits of lime crystals; capillitium rather scanty, variable, consisting 

 usually of a network of colorless or purplish, stout or slender threads, 

 sometimes with vesicular expansions enclosing lime crystals; spores 

 brownish purple, marked with short spines which are scattered or 

 grouped in clusters, rarely with patches of broken reticulation, the 

 spore wall often traversed by a low ridge, 9-10 /x. Plasmodium colorless. 



Oregon; Europe. 



3. Physarina von Eohnel 



Sitzungsb. K. Akad. Wiss. Wien, Math.-Nat. Kl. 118 (1) : 431. 1909. 



Sporangia rough with numerous blunt, cylindrical, peg-like processes 

 projecting from the surface; capillitium without nodes. 

 One species. 



Physarina echinocephala von Hohnel 



Sitzungsb. K. Akad. Wiss. Wien, Math.-Nat. Kl. 118 (1) : 432. 1909. 



PL XXI, Fig. 573. 



Sporangia gregarious, stalked, subglobose, 0.4-0.5 mm. in diameter, 

 pale pink or flesh colored in herbarium, blackish brown when gathered; 

 outer layer of sporangium somewhat cartilaginous, bearing numerous 

 cylindrical processes filled with lime; inner wall smooth, membranous; 

 stalk stout, tapering, furrowed, flesh colored to nearly white, filled 

 with lime, continued above into a pale subglobose columella; capillitium 

 violet-brown, paler and branching at tips; spores nearly smooth, 

 brownish violet, 7-9 fi. 



Java. 



4. Diderma Persoon 

 Roem. N. Mag. Bot. 1 : 89. 1794. 

 1873. Chondrioderma Rost., Versuch 13. 



Sporangia plasmodiocarpous or distinct, sessile or stipitate; peridium 

 as a rule double, the outer wall generally calcareous with the lime gran- 

 ules globular, non-crystalline, the inner wall very delicate and often, 



