94 Mycetozoa of North America 



Sporangia gregarious, white or bluish white; stalks and 

 columellae white or cream-colored; capillitium colorless. 



Type locality: Switzerland. 



Habitat: On mosses and dead leaves in wet places. 



Distribution: *Iowa, New York, Ontario, Pennsylvania, 

 Virginia; var. album, Ontario. 



Illustration: Lister, Mycetozoa ed. 3. pi. 207. 



This species is very close to D. radiatum var. umbilicatum, 

 and may be only a phase thereof. There are no sharp distin- 

 guishing characters, so that habit and habitat are important. 

 The sporangia are scattered, or in small groups, on moss and other 

 ground material in wet places, and often associated with Lampro- 

 derma colunibinum (Pers.) Rost. Such collections, and conform- 

 ing closely to the description, are usually this species. Any or all 

 of the characters may, however, be found in phases of Z>. radiatum, 

 although that species is usually on wood, and the sporangia are 

 more closely crowded. Var. album was found by Mr. Eli Davis 

 twice, in different years, at Komoko, Ontario, associated with the 

 typical form. 



2. Diderma hemisphericum (Bull.) Hornem. Fl. Dan. 33: 13. 

 1829. 



Relicidaria hemispherica Bull. Herb. Fr. pi. 446, fig. 1. 1789; Bull. Champ. 

 93. 1791. 



Plasmodium opaque white (Lister). Sporangia scattered, 

 flat, discoid, on a central stalk, 0.6 to 1.2 mm. diam., occasionally 

 sessile and confluent, chalk-white; sporangial wall of two layers 

 on the upper, flat surface; the outer a smooth crust composed 

 of globular lime-granules, 1-3 ^ diam., easily separating and 

 breaking away from the more persistent, membranous inner layer; 

 under surface rugose, thickened. Stalk ochraceous or brownish, 

 0.2 to 0.8 mm. long, thick, furrowed with wrinkles which are con- 

 tinued over the flat under side of the sporangium, densely cal- 

 careous, often seated on a white hypothallus. Columella con- 

 sisting of the broad, thickened base of the sporangium, reddish 

 or brownish, charged with calcareous deposits, usually in the form 

 of nodules or large rhomboidal crystals. Capillitium of slender, 

 colorless threads, branching and anastomosing, or of violet-brown 

 threads sparingly branched except at the pale extremities. 

 Spores pale violet-brown, nearly smooth, 7-9 n diam. 



