The Myxomycetes of Eastern Iowa. 155 



A very variable species. Our specimens do not agree in 

 several particulars with the description above given, which is 

 substantially that of Rostafinski. As will be seen from the 

 plate, it is the outer peridium that is with us white and bur- 

 dened with lime, the inner is simple and comparatively thin. 

 The snowy outer peridium is however easily displaced. The 

 colony may not show it at all, in which case the peridia 

 remaining give to the fructification entire a pale lead color, 

 very characteristic. The nodes of the capillitium are not gen- 

 erally round, and the spores in our specimens measure much 

 larger than as quoted, viz: .016-.018, the largest spores we 

 have seen. Withal a handsome and attractive species, not 

 common. Found on decaying wood in August. Mr. Newton. 



57. Physarum cinereum, Batsch. Plate IX, Figs. 4, 4a, 



afi and 4c. 



Sporangia sessile, crowded, of different sizes, spherical 

 elliptical or elongate, flattened. Capillitium strongly devel- 

 oped, richly supplied with large irregular angular calcareous 

 nodes. Columella none. Spores smooth or finely punctate, 

 .0075-.013, violet-black. 



This delicate inconspicuous species is well defined by the 

 characters given. It occurs not rarely on richly manured 

 ground, in meadows, lawns, or even on the open prairie. The 

 Plasmodium may form rings several inches in diameter, scat- 

 tered here and there over a surface several square feet in 

 extent, in fruit ascending the blades of grass, completely 

 covering these with the crowded sporangia. The color of 

 the fruit is well described in the specific name, cinereiivi^ 

 ashen-gray. The spores are very delicately papillate. 



58. Physarum ditmari, Rostafinski. Plate VIII, Figs. 7 



and *]a. 



Sporangia sessile, crowded or heaped, spherical, ovoid or 

 elongate, yellow or greenish-yellow. Peridium thin, fragile. 



