Stemonitis 143 



grayish violet or brownish violet, 6-8 /x diam., faintly or strongly 

 spinulose, the spines arranged in a more or less reticulate pattern, 



Var. flaccida Lister, Mycetozoa ed. 2. 144. 1911. 



Sporangia weak; capillitium scarcely forming a surface-net, 

 or a net with very wide meshes connected by a few slender threads 

 to the columella. 



Var, nigrescens (Rex) Torrend, Fl. Myx. 141. 1909. 



Stemonitis nigrescens Rex, Proc. Acad. Nat. Sc. Phila. 1891: 392. 1891. 

 (N. Y. B. G. nos. 6183, 11961, type material.) 



Developments separated into numerous small groups of clus- 

 tered sporangia, each group on a common hypothallus; sporangia 

 4 to 5 mm. high, almost black, with short stalks, the capillitium 

 often close to the base of the stalk; capillitium often lax with 

 incomplete surface-net, sometimes complete; spores grayish vio- 

 let, darker and larger than in the typical form, 8-9 /x diam. 



Type locality: Europe. 



Habitat : On dead wood ; var. nigrescens on leaves, mosses, and 

 ground sticks in moist places. 



Distribution: Common and abundant throughout North 

 America, except the varieties which are not common. 



Illustrations: Lister, Mycetozoa ed. 3. pi. 118; pi. 125, figs. 

 n-p. 



This species is readily recognized by the reticulate arrange- 

 ment of the spines on the spores. This may occasionally be 

 partly incomplete, and strongly or weakly marked. The spores 

 in practically all American specimens here range from 6-8 n, diam., 

 with few a little larger, and the color may be grayish or brownish. 

 Var. flaccida is rare. It bears about the same relationship to 

 typical 5. fusca that the more common 5. splendens var. flaccida 

 bears to the typical form. Such forms are not true varieties, but 

 produced when conditions are unfavorable at the time of develop- 

 ment. Poorly developed forms of Comatricha longa may be mis- 

 taken for S. fusca var. flaccida, as the spores are similar. Typical 

 var. nigrescens is quite common in the mountains of northeastern 

 Pennsylvania, occurring on leaves, mosses and ground sticks, the 

 Plasmodium inhabiting the soil instead of rotten wood, the latter 

 being always the habitat for the typical form of 6". fusca. The 

 type specimen of Rex was collected in Pennsylvania, and the fact 

 that it is on wood has little significance. It is the common prac-, 

 tice to include with the variety all very small dark phases of 



