Arcyria 249 



transversely banded or spinulose, the spines often stouter and 

 larger on one side; threads composing the basal threads of the 

 network 4-6 n diam., either smooth, faintly warted or reticulate, 

 with numerous attachments to the cup; the threads sometimes 

 looped to form a more or less complete surface-net. Spores 

 almost colorless, marked with a few scattered warts, 6-8 n diam. 



Var. digitata (Schw.) G. Lister, Mycetozoa ed. 3. 232. 1925. 

 Stemonitis digitata Schw. Trans. Am. Phil. Soc. II. 4: 260. 1832. 

 Arcyria digitata (Schw.) Rost. Mon. 274. 1875. 



Sporangia cylindrical, usually on long stalks, adhering in clus- 

 ters of two to twelve or more. 



Type locality: France. 



Habitat: On dead wood, twigs, or leaves. 



Distribution: Common and abundant throughout North 

 America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 176, figs. a-e. 



Var. digitata is hardly worth recognition as a variety, much 

 less as a species. Free and clustered sporangia are found to- 

 gether in many collections and undoubtedly come from the same 

 Plasmodium. Similar conditions are found in Hemitrichia Ves- 

 parium, Trichia Botrytis, T. floriformis, and other species, where 

 they are covered in a broader description. In other gatherings 

 of A. cinerea the stalks do not adhere, but the sporangia are in 

 small groups, the free stalks curved or bent and leaning to each 

 other. A. cinerea is also very variable and there are many de- 

 partures from the typical form, much of the variation depending 

 on atmospheric changes. 



4. Arcyria carnea G. Lister, Jour. Bot. 59: 92. 192 L (N. Y. 

 B. G. no. 12242, authentic material.) 



Arcyria cinerea (Bull.) Pers. var. carnea Lister, Mycetozoa ed. 2. 236. 1911. 

 Arcyria carnea (?) Schum. Enum. PI. Saell. 2: 213. 1803. 



Plasmodium? Sporangia stalked, loosely clustered, ovoid or 

 short-cylindrical, flesh-colored, L5 mm. high; cup marked with 

 papillae or a broken reticulation, giving attachment to the capilli- 

 tium. Stalks short, 0.2 to 0.4 mm. high. Capillitium a compact 

 network of pale flesh-colored threads about 3.5)U diam., marked 

 with close-set prominences arranged in a loose spiral and appear- 

 ing square-ended, notched, or hammer-shaped in profile; remain- 

 der of the thread either spinulose or marked with a broken reticu- 



