COMATRICHA 179 



1889. Comatricha nigra (Pers.) Schroeter, Pilz. Krypt. Fl. <v. Schles., I., 

 p. 118. 



1894. Comatricha obtusata Fr,, Lister, Mycetozoa, p. 117. 



1899. Comatricha nigra (Pers.) Schroeter, Macbr., A^. A. S., p. 128. 



Sporangia scattered, ferruginous or dark brown, globose or ovoid, 

 stipitate; stipe long, hair-like, tapering upward, black; hypothallus 

 none; columella rapidly diminished toward the top, at length dissi- 

 pated ; capillitium of slender flexuous threads, radiating horizontally, 

 repeatedly branching and anastomosing to form an intricate dense 

 network, from the surface of which project a few short hook-like 

 peridial processes; spore-mass black, spores by transmitted light dark 

 violaceous, smooth or nearly so, 7-10 /x. 



This species, when typical, is easily recognized by its almost globose 

 sporangia mounted on long slender stocks. These are 2 or 3 mm. 

 high and generally persist, as Persoon noticed, a long time after the 

 sporangium has fallen. The sporangia are at first black; after spore 

 disposal pale ferruginous. In shape they vary from ovate to spherical. 

 Sometimes they are umbilicate below, so that a vertical section would 

 be obcordate. Care must be taken to distinguish the present species 

 from blown-out forms of Lamproderma. 



This most common species seems to be also the center of widest 

 differentiation. In a valuable paper on the Myxomycetes of Dr. 

 C. H. Peck's Herbarium Dr. Sturgis points out the varying relation- 

 ships of a group of surrounding forms. According to account C. 

 nigra verges on one side to C. laxa, on the other to aequalis which 

 the Listers enter as varietal here. However, in the former the more 

 rigid, direct and simple branching from the columella is usually de- 

 terminative; in the latter the color, form, and generally more deli- 

 cate structure, and a tendency to grow in tufts will serve to dis- 

 tinguish. 



In this discussion we have assumed as typical the globose sporan- 

 gium, with the variations in the direction of ovate, obovate, ellip- 

 soidal, etc., the capillitium flexuous and more richly anastomosing 

 near the columella. On the drier slopes m the mountains of Colo- 

 rado specimens are especially abundant, in proper season covering 

 apparently the lower surface of every barkless twig or fallen stem or 

 tree entire! In such a field one might imagine every possible varia- 



