ARCYRIA 



271 



green or grayish brown, curved, weak, 0.2-0.3 mm. high, filled with 

 spore-like cells; capillitium elastic, threads pale, 2.5-3 /x in diameter, 

 with many attachments to the cup and a few rounded free ends, 

 marked with a loose spiral of prominent cogs and sometimes scat- 

 tered spinules and irregular reticulations; spores pale glaucous, nearly 

 smooth, 7 ix. 

 Japan, rare. 



12. Arcyria cinerea {Bull.) Pers. 



Syn. Meth. Fung. 184. 1801. 

 PI. XVII, Figs. 459, 460. 



1791. Trichia cinerea Bull., Champ. 120. 



1791. Stemonitis cinerea (Bull.) Gmel., Syst. Nat. 2 : 1467. 



1794. Arcyria albida Pers., Roemer N. Mag. Bot. 1 : 90. 



1797. Stemonitis glauca Trentep., in Roth, Cat. Bot. 1 : 221. 



1838. Arcyria trichioides Corda, Icones 2 : 23; pi. 12, fig. 86. 



1876. Arcyria friesii Berk. & Br., Ann. Mag. Nat. Hist. IV. 17 : 140 



1877. Comatricha alba Schulz., Just Bot. Jahresb. 155. 

 1892. Arcyria cookei Massee, Mon. 154. 



1896. Arcyria tenuis Schroet, Hedwigia 35 : 207. 



Sporangia scattered or gregarious, ovoid or cylindrical, generally 

 tapering upward, rarely almost globose, about 2-3 mm. high, typically 

 ash gray, but sometimes with a yellowish tinge, rarely rose or green, 

 stipitate; calyculus very small, thin; stipe slender, about half the total 

 height, rising from a small hypothallus, gray or blackish, densely 

 crowded with spore-like cells; capillitium dense, freely branching, 

 ashen or yellowish, 3-4 /x, wider below, minutely spinulose; spore- 

 mass concolorous; spores by transmitted light colorless, smooth, 6-7 xx. 

 Plasmodium gray, white or yellowish. 



A very common little species, easily recognized in its typical ex- 

 pression by its color and habit. The capillitium is more dense than in 

 any other species and expands somewhat less vigorously than in most. 

 The stipe is about equal to the expanded capillitium, unusually long. 

 The Plasmodium occurs in rotten wood, especially species of Tilia, 

 and judging from the number of sporangia found in one place, is usu- 

 ally scanty. Bulliard gives the first account of the species by which 

 it can with any certainty be identified. 



Maine to Alaska, and south to Mexico, Nicaragua, West Indies, 

 South America. World-wide in its distribution. 



Arcyria nigella Emoto (Bot. Mag. 42 : 201, 1928), described from 

 Japan, is a minute form sometimes showing bluish tints, with a weak 

 capillitium, spores given as 7-9 xx and a strongly netted calyculus. 

 The photographic illustration of the spores, at a magnification given 



