120 Mycetozoa of North America 



flattened plasmodiocarps 2 to 12 mm. across, 0.15 mm. thick; 

 sporangia! wall of two layers; outer layer an eggshell-like crust 

 of closely combined large stellate crystals of lime, often extending 

 beyond the broad, membranous base of the sporangium, and 

 powdered with free crystals, which often break away entirely; 

 inner layer membranous. Columella none. Capillitium profuse, 

 of rigid, dark purplish brown or pale threads, anastomosing 

 chiefly above and below, more or less connected by bars, and 

 attached by slender, colorless branches to the sporangial wall. 

 Spores violet-gray, spinulose or nearly smooth, 8-15 m diam. 



Type locality: England. 



Habitat: On dead leaves and stems. 



Distribution: *Bermuda, *Iowa, Kansas. 



Illustration: Lister, Mycetozoa ed. 3. pi. 105, as D. dubium. 



The Kansas collections are probably as representative of this 

 species as may be found in North America. They consist of 

 thinly effused, flattened plasmodiocarps, similar to those of D. 

 squamulosum and D. complanatiim. From the former it is dis- 

 tinguished by the connecting bars of the threads of the capil- 

 litium, and from D. complanatum by the absence of vesicles in 

 the capillitium. 



5. Didymium vaccinum (Dur. & Mont.) Buchet; Buchet, Cherm. 

 & Evrard, Bull. Soc. Myc. Fr. 36: 110. 1920. 



Diderma vaccinum Dur. & Mont. Expl. Sc. Alg. Bot. 1: 408. 1848. 

 Didymium Trochus Lister, Jour. Bot. 36: 164. 1898. (N. Y. B. G. no. 13080, 

 authentic material.) 



Plasmodium bright yellow (Lister). Sporangia scattered, 

 hemispherical or turbinate, 0.6 to 1 mm. diam., short-stalked or 

 sessile, rarely forming plasmodiocarps, smooth, white or cream- 

 colored; sporangial wall readily falling away entire, and consist- 

 ing of two layers; outer layer brittle and shell-like, composed of 

 closely compacted angular or stellate crystals of lime, forming a 

 hemispherical cap fitting upon the yellowish brown, thickened 

 margin of the large hemispherical columella; inner layer mem- 

 branous, usually adhering to the outer layer. Stalk obconical 

 or shortly cylindrical, yellowish brown, 0.2 to 0.4 mm. high, 

 filled like the columella with stellate crystals of lime. Capilli- 

 tium consisting of rigid and persistent colorless or purplish brown 

 threads, nearly simple or branched, sometimes expanded below 



