DICTYDIUM 221 



to be compared with C. minutissima, from which its color instantly 

 distinguishes it. Usually on very rotten basswood, Tilia americana, 

 but reported on a variety of substrata. Characterized by the minute, 

 bell-shaped, violet sporangia with a few large, flat nodes. 



Pennsylvania, Florida, Illinois, Iowa, West Indies; Europe, 

 Kamerun, Ceylon, Malay Peninsula, Japan. 



3. Dictydium Schrad. emend. Rost. 

 Vers. 5. 1873. 

 1797. Dictydium Schrad., Nov. Gen. PL 11, in part. 



Sporangia distinct, gregarious, globose or depressed-globose, stipi- 

 tate, cernuous; peridium very delicate, evanescent, thickened on the 

 inside by numerous meridional costae which are joined at frequent 

 intervals by fine transverse threads more or less parallel to each other, 

 forming a persistent network of rectangular meshes. 



Schrader applied the name Dictydium to all Cribraria-like species 

 in which the calyculus was wanting, and in this was followed by Fries 

 (Syst. Myc. 3 : 164). Rostafinski first defined the genus in its modern 

 sense. 



We here recognize a single species, extremely common, and widely 

 distributed throughout the world. It is remarkably variable, and 

 many of its more constant variants have been deemed worthy of 

 varietal and even specific distinction. 



Dictydium cancellatum (Batsch) Macbr. 



N. A. Slime-Moulds 172. 1899. 

 PL XV, Figs. 371, 372. 



1789. Mucor cancellatus Batsch, Elench. Fung. Cont. 2 : 135. 



1791. Stemonitis cancdlata (Batsch) GmeL, Syst. Nat. 2 : 1468. 



1796. Cribraria cernua Pers., Obs. Myc. 1 : 91. 



1797. Dictydium umbilicatum Schrad., Nov. Gen. PL 11, pi. 4, fig. 1. 

 1808. Trichia cernua (Pers.) Poir., in Lam. Encycl. 8 : 54. 



1816. Dictydium cernuum (Pers.) Nees, Syst. Pilze 120. 



1826. Cribraria trichioides Chev., Fl. Par. 327. 



1893. Dictydium longipes Morg., Jour. Cin. Soc. Nat. Hist. 15 : 143. 



Sporangia gregarious, depressed-globose, nodding, the apex at length 

 umbilicate, stipitate, brown or brownish purple; stipe varying in 

 length from two to ten times the diameter of the sporangium, attain- 

 ing 5-6 mm., generally erect, more or less twisted and pallid at the 

 apex, below dark brown, with hypothallus small or none; calyculus 

 often wanting, when present a mere film connecting the ribs of the 



