58 THE MYXOMYCETES 



22. Physarum conglomeratum Rost. 



Mon. 108. 1875. 



1886. Physarum ochraceum Schroet., Krypt.-Fl. Schles. 3 (1) : 130, non Diderma 



ochraceum Hoffm. 1795. 

 1892. Physarum rostafinskii Mass., Mon. 301. 



Sporangia depressed, globose or irregular, sessile, more or less ag- 

 gregated and often angular by mutual pressure, 0.3-0.5 mm. broad, 

 ochraceous yellow; peridium double, the outer thick, cartilaginous, at 

 length irregularly ruptured and reflexed, disclosing the more delicate, 

 ashen gray inner membrane which encloses capillitium and spores; 

 capillitium abundant, showing large, white irregular calcareous thick- 

 enings which are often consolidated and in some sporangia tend to 

 aggregate at the center forming a pseudocolumella ; spore-mass brown, 

 spores violaceous, slightly roughened, 8-10 /jl. 



This beautiful species shows a peridium as distinctly double as in 

 any diderma. The outer peridium is reflexed exactly as in some 

 species of that genus; is yellow without, white within and withal long- 

 persistent. The capillitium of course distinguishes the species instantly 

 as a physarum. It is distinguished from P. contextum by the size of 

 the spores. This being a decisive specific character the synonymy 

 prior to Rostafinski is uncertain. The specific name adopted by the 

 Polish author is therefore approved, although perhaps not the earliest. 



Rare in North America, but widely distributed there and in Europe ; 

 India. 



23. Physarum contextum Pers. 



Syn. Meth. Fung. 168. 1801. 

 PL VI, Figs. 101, 102. 



1796. Diderma contextum Pers., Obs. Myc. 1 : 89. 



1818. Didymium contextum Fr., Symb. Gast. 20. 



1849. Leocarpus contextus Fr., Summ. Veg. Scand. 450. 



1873. Diderma ochroleucum Berk. & Curt., Grev. 2 : 52. 



1876. Diderma flavidum Pk., Rept. N. Y. State Mus. 28 : 54. 



1892. Physarum conglomeratum Mass., Mon. 304, non Rost. 



Sporangia distinct or subplasmodiocarpous, sessile, densely crowded, 

 oval, reniform or elongated, 0.3-0.6 mm. wide; peridium double, the 

 outer rather thick, calcareous, yellow or yellowish white, rarely pink- 

 ish buff, the inner thin, yellowish or pallid; capillitium white, con- 

 taining numerous large, irregular calcareous granules; columella none; 

 spores deep violet, distinctly and irregularly spinulose, 11-13 ix. 



This singular species occurs not rarely upon the bark of fallen twigs, 

 upon bits of straw or grass stems lying undisturbed upon the ground. 



