DIDYMIUM 89 



color, frosted with minute crystals of lime, breaking irregularly ; 

 stipe, when present, short, stout, dull black, opaque, arising from 

 a broad base or hypothallus ; columella large, prominent ; dark- 

 colored, rough above, concave below ; capillitium of more or less 

 sinuous, usually dark-colored threads, sparingly branched, and 

 often with calycif orm thickenings ; spore-mass black, spores by 

 transmitted light pale, purplish gray, spinulose or rough, 10-12 /A. 



A well-marked and common species, distinguished by its 

 depressed sporangium and dark-colored, opaque stipe. The 

 latter is usually very short, almost completely concealed in the 

 concavity of the umbilicate sporangium. The columella is dark 

 colored, forming the floor of the peridial cavity. 



Persoon first named this species as here. Later on, Usters 

 Ann., XV., 6, he substituted villosum as a more appropriate 

 specific name. Schrader rejects both names given by Persoon 

 as unsuitable, and suggests farinaceum. Schrad., op. cit., p. 27. 



New England, Ohio, Missouri, Alabama, Iowa, Nebraska. 



6. DIDYMIUM MINUS Lister. 



PLATE X., 4, 4 a, 4 b. 



1892. Didymium farinaceum Schr., var. minus, Lister, Mycetosoa, p. 97. 

 1896. Didymium //linus Lister, Morgan, Jour. Cin. Soc., p. 61. 



Sporangia gregarious, depressed globose, umbilicate below, 

 whitish or gray, small, about -| mm., stipitate ; stipe erect, 

 rather slender, black, faintly striate, about equal to the sporan- 

 gium in the horizontal diameter ; columella distinct, dark brown, 

 globose or depressed globose, attaining in some cases the centre, 

 rough ; capillitium delicate, almost colorless, radiating, sparsely 

 branched ; spores in mass dark brown, by transmitted light 

 violet tinted, minutely roughened, S-io p. 



Probably more common than the preceding, and generally 

 mistaken for it. Distinguished by its smaller size, longer and 

 more slender stem, and general trim, well-differentiated appear- 

 ance. Certainly very near the preceding, of which Mr. Lister 

 regards it as merely a variety. 



New York, Ohio, Iowa. 



