236 A Monograph of the MyxogaMres. 



Didymium eflFusum, Rost. 



Sporangia densely aggregated or scattered, sr.ssi/e on a hroad 

 hasc, circular or irregular in outline, dcjyrcsscd, wall grey, pruinose 

 with numerous minute crystals aggregated in masses; columella 

 hemis2oherical, white or pallid, rugulose ; threads of capillitium 

 very slender, colourless or pale inXiguxoxxs,, furnished with scat- 

 tered coloured protuherances, combined to form an irregular dense 

 net; spores globose, brownish-purple, minutely warted, 10 — 12 ju, 

 diameter. 



Didymium effusum, Rost., Mon., p. 163; Sacc, Syll, no. 1302. 



On leaves, wood, &c. Britain (Cornwall) ; Finland ; Sweden ; 

 France ; Germany ; United States ; Ceylon. 



About '5 mm. diameter, characterized by the white columella, 

 the capillitium threads furnished with numerous well-defined 

 projections in the form of thickened plates or pyriform swellings, 

 and the dense meal of crystals on the wall. 



(Rostafinski's Synonyms.) 

 Diderma effusum, Link, Obs. I., p. 42 (1809). 

 Didymi'um effusum, Fr., 1. c, iii., p. 124 (1829). 

 Pliysarum conjlucns, Fr., Excl. Syu., 1. c, iii., p. 146 (1829). 



Sub-Gen. Hemididymium . 



Capillitium usually dense, threads branching and anastomosing 

 to form an irregular network throughout the capillitium, angles 

 usually flattened and more or less triangular. 



The species included in the present sub-genus are distin- 

 guished from those belonging to the sub-genus Didymium by 

 the absence of the simple or bifurcating threads at the basal 

 portion of the capillitium. 



A. Siwrangium stipitate. 



* Sjjores smooth. 



Didymium longipes, Mass. (n. sp.) (fig. 226). 



Sporangia small, globose, snoiv-v:hitc, frosted with a few 

 scattered granules or crystals of lime ; stem very long and 



