118 THE NORTH AMERICAN SLIME-MOULDS 



Resembling plasmodiocarpous forms of D. squamulosum, a mon- 

 tane var. ; small and delicate, our specimen about 16X6 mm. Evi- 

 dently not common; collected but once by Professor Bethel at an 

 altitude of 11,000 feet. Rocky Mountains of Colorado. 



Reported in Switzerland and Sweden. 



In certain Swiss gatherings made in 1913 Miss Lister finds capil- 

 litial threads with spiral taenias as in Trichia! {Jour, of Bot., Apr. 

 1914.) The threads in our specimen are roughened, somewhat as in 

 D. squamulosum, though less strongly; the spores are nearly smooth, 

 fuliginous at first, paler and violaceous when saturate. 



4. DiDYMIUM FULVUM Sturgis. 



1917. Didymium fulvum Sturgis, Mycologia, IX., p. 37. 



Sporangia gregarious, sessile, elongate or forming curved plasmo- 

 diocarps, sometimes confluent, rarely subglobose, concave beneath, 

 pale-raw-umber in color, 0.5-0.8 mm. in diameter, occasionally seated 

 on a concolorous, membranous, lime-encrusted hypothallus which may 

 form pseudo-stalks; sporangium wall membranous, stained with yel- 

 low blotches, thickly sprinkled with clusters of large acicular crystals 

 of pale-yellowish lime; columella very much flattened or obsolete; 

 capillitium an abundant network of delicate, almost straight or flexu- 

 ose, pale-purple or nearly hyaline threads, frequently with dark, 

 calyciform thickenings as in Mucilago, and occasionally showing 

 fusiform, crystalline blisters; spores dark-purplish-brown, coarsely 

 tuberculate, the tubercles usually arranged in curved lines, paler and 

 smoother on one side, 12.5 to 14.5 /x. Colorado. 



5. Didymium crustaceum Fr. 



1829. Didymium crustaceum Fr., Syst. Myc, III., p. 124. 



Sporangia closely aggregated, globose, or by compression deformed, 

 sessile, snow-white, by virtue of the remarkably developed covering 

 of calcareous crystals by which each sporangium is surrounded as if 

 to form a crust, the peridium membranous, colorless, usually shrunk- 

 en above and depressed; columella pale, small, or obsolete; hypothal- 

 lus scant or vanishing; capillitium of rather stout violaceous threads 

 seldom branched except at the tips, where they are pale and often 



