106 Mycetozoa of North America 



brownish, or red-brown, often mottled or areolate with pale lines 

 of dehiscence; sporangial wall dehiscing in a stellate manner by 

 revolute lobes, white or pale brown on the inner side, the outer 

 layer cartilaginous, with granular deposits of lime, closely con- 

 nected with the membranous inner layer. Stalk ochraceous or 

 reddish brown, usually short and stout, enclosing white lime de- 

 posits. Columella hemispherical or subglobose, often large, 

 white, cream-colored, or red-brown, densely calcareous. Capil- 

 litium abundant, dark violet-brown, radiating from the columella 

 in somewhat rigid threads, sparingly branched except at the 

 colorless extremities, rarely pale, slender, and flexuose. Spores 

 purplish brown, often paler, closely and minutely spinulose, 9-12 )u 

 diam. (Plate 9, fig. 5.) 



Var. umbilicatum (Pens.) Meylan, Ann. Conserv. Bot. Geneve 15-16: 312. 1913. 

 Diderma umbilicatum Pars. Syn. Meth. Fung. 165. 1801. 



Sporangia smaller, white or gray, umbilicate beneath, de- 

 hiscing irregularly. 



Type locality: Sweden. 



Habitat: On dead wood. 



Distribution: Throughout the United States and Canada. 



Illustrations: Lister, Mycetozoa ed. 3. pi. 93; pi. 94, figs, 

 a, b. 



This species is not common in eastern North America, and 

 colonies are usually small. The many large collections made by 

 Bethel, and by Sturgis, in Colorado, indicate it is more of a 

 western mountain-form. Var. umbilicatum is rare after removal 

 of forms now regarded as D. montanum. The color of the spores 

 is dark in only occasional specimens. Usually they are normal 

 purplish brown, and frequently paler, which also applies to some 

 European collections. Specimens of D. radiatum, D. radiatum 

 var. umbilicatum, and D. montanum, from Switzerland, courte- 

 ously sent by M. Ch. Meylan, have pale spores in all three. 

 Two other varieties, found in Europe, have not been reported 

 from North America. 



17. Diderma roanense (Rex) Macbr. N. A. Slime-Moulds 104. 

 1899. 



Chondrioderma roanense Rex, Proc. Acad. Nat. Sc. Phila. 1893: 368. 1893. 



Plasmodium? Sporangia scattered, stalked, discoidal and 

 flattened, or slightly convex, 0.8 to 1.2 mm. diam., mottled red- 



