66 THE MYXOMYCETES 



stipe conical, short, about equal to the sporangium, somewhat wrin- 

 kled, white or yellow; sometimes tawny; columella small but distinct, 

 concolorous with the stipe; hypothallus white, scanty, often lacking; 

 capillitium abundant, snow-white, with rather large angularly stellate 

 nodes; spores pale violet by transmitted light, almost smooth, 7.5-10 ju. 

 Plasmodium yellow. 



Easily distinguished by its pale stipe and columella and white capil- 

 litium in contrast with the yellow peridial walls. N. A. F. 1395 is this 

 species. Massee refers it erroneously to P. schumacheri Spreng. The 

 description and specimen do not correspond. By that name the species 

 has, however, been hitherto known in the United States. In culture 

 brilliant orange sclerotia are formed on a white, strand-like hypothal- 

 lus. 



Common in the eastern United States, rare west of the Mississippi, 

 Puerto Rico, Brazil, Bolivia; world-wide. 



36. Physarum citrinum Schum. 



Enum. PL Sail. 2 : 201. 1803. 



1818. Physarum compactum Ehr., Sylv. Myc. Berol. 26. 



1827. Physarum schumacheri Spreng., Syst. Veg. 4 : 528. 



1829. Diderma citrinum (Schum.) Fr., Syst. Myc. 3 : 100. 



1846. Physarum aureum var. chrysopus Lev., Ann. Sc. Nat. Bot. 3 ser. 15 : 166. 



1876. Physarum leveillei Rost, Mon. App. 7, in part. 



1896. Cytidium citrinum (Schum.) Morg., Jour. Cin. Soc. Nat. Hist. 19 : 9. 



Sporangia gregarious, scattered, globose, 0.4-0.7 mm. in diameter, 

 somewhat flattened below, pale yellow, citrine, stipitate or nearly 

 sessile; peridium thin, covered almost completely with small calcareous 

 scales; stipe stout, erect, fragile, tapering upwards, furrowed, yellow, 

 opaque, arising from a small hypothallus which is sometimes continu- 

 ous from one sporangium to the next; columella small, conical, yellow; 

 capillitium a rather dense, delicate network, the calcareous nodules 

 yellow, numerous, roundish, and generally small; spore -mass black; 

 spores under the lens violaceous, almost smooth, about 8-10 /x. 



This species seems to be rare in the United States. It somewhat 

 resembles P. melleum, from which it is distinguished by its brighter 

 color and yellow nodes, and its denser capillitium. P. galbeum is a 

 smaller form, and lacks the columella. Rostafinski strangely confused 

 the synonymy. 



Var. sessile Meylan is reported from Switzerland and Rumania. In 

 our material it seems to merge into the typical form. 



New England, Ohio, Colorado, Washington, South America; 

 Europe, South Africa, Australia. 



