Arcyria 253 



Illustration: Lister, Mycetozoa ed. 3. pi. 181. 



The variety dispersa has been found at three widely separated 

 locaHties on Long Island, New York, on one occasion in great 

 abundance on thousands of leaves of the scrub oak. Var. major 

 G. Lister (Mycetozoa ed. 3. 236. 1925) may occur in North 

 America, but is difficult to understand. Many collections, on 

 wood, consisting of large sporangia in clusters 10 mm. or more 

 across, have the color of A. insignis, but in the great majority, 

 the capillitium is centrally attached, and such forms are un- 

 doubtedly -4. incarnata irrespective of the markings on the capilli- 

 tium. Among the others are several that have the capillitium 

 firmly attached to the cup, and with cogs or square-ended promi- 

 nences on the capillitium, exactly like those on the capillitium of 

 an authentic specimen of A. carnea, and I have placed them with 

 that form. Still others, with capillitium firmly attached, do not 

 have the cogs, but the threads of the capillitium are not as narrow 

 as those of A. insignis and those are placed with A. denudata. 

 None of the forms referred to have the narrow threads. Critical 

 separations on the markings of the capillitium are very unsatis- 

 factory, as particular features are not sharply restricted to any 

 of the four species mentioned. It might be better, perhaps, to 

 divide all these obscure forms among A . incarnata and A . denu- 

 data on the attachment of the capillitium solely, abandoning 

 thereby A. insignis var. major and A. carnea. 



9. Arcyria incarnata Pers. Obs. Myc. 1: 58. 1796. 

 Stemonitis incarnata Pers.; Gmel. Syst. Nat. 2: 1467. 1791. 



Plasmodium white (Lister). Sporangia stalked or nearly 

 sessile, crowded, subcylindrical or ellipsoid, 1 to 1.5 mm, high, 

 0.6 mm. broad, pink; cup of sporangium membranous, even or 

 plicate, spinulose. Stalk weak, 0.1 to 0.3 mm. long, flesh-colored, 

 filled with spore-like cells. Capillitium a very loose, elastic, 

 expanding network of pale pink threads 3-5 n diam., sparingly 

 and somewhat irregularly branched, with here and there broad, 

 perforated or ring-like expansions, often swollen at the axils of 

 the branches; thickenings in the form of sharp cogs, half-rings, or 

 spines arranged in a loose spiral, and of minute scattered spinules; 

 free ends more or less numerous, clavate or pointed, spinose. 

 Spores pale pink, marked with a few scattered warts, 6-8 ix diam. 



Var. fulgetjs Lister, Mycetozoa ed. 2. 242. 1911. 



