COMATRICHA.] STEMOXITACE-E. 117 



The genus Comatricha is a somewhat artificial one ; it includes 

 species which agree with Lamproderma in all characters but the per- 

 sistent sporangium-wall, and with Sf> ///</// <v;x in all but the presence of 

 the superficial net of the capillitium ; in C. typhoides the surface net is 

 often developed on the lower half of the sporangium ; at the same 

 time it is a useful genus, typically marked by the uniform network of 

 the capillitium and by the isolated, not fasciculate, growth of the 

 sporangia. 



KEY TO THE SPECIES OF COMATRICHA. 



A. Spores dark, brownish-violet, or grey : 



a. Spores nearly smooth 



Capillitium dense, crisped, and flexuose throughout ; on 

 wood. 1. C. obtusata 



Capillitium large, primary branches stout and nearly 

 straight ; 011 wood. '2. C. laxa 



b. Spores spinulose 



Sporangia globose ; on leaves. 3. C. lurida 



Sporangia much elongated, slender and cylindrical ; on 

 wood. 4. C. longa 



B. Spores pale, lilac, or reddish-lilac : 



a. Spores marked with a few widely scattered warts, the 



remaining surface nearly smooth or delicately reti- 

 culated, 4 to 6 /A diam. ; on wood. 5. C- typhoides 



b. Spores spinulose, 6 to 10 //, diam. 



Sporangium-wall completely evanescent ; on leaves. 



6. C. Persoonii 



Sporangium-wall persistent at the base as a membranous 

 cup ; on leaves. 7. C. rubens 



1. Comatricha obtusata Preuss, I.e., p. 141 (1851). Plas- 

 niodium wat-ry-whitf. in rotten wood, maturing at the place of 

 emergence. Total height 1 to 6 mm. Sporangia globose, ellipsoid 

 or cylindrical, stipitate, scattered or gregarious, about 0'6 mm. 

 diam., purplish-brown ; sporangium-wall evanescent. Stalk 

 subulate, slender, black, shining; in the globose form usually 

 2 to 6 times the length of the sporangium ; equalling the length 

 of the sporangium, or shorter in the cylindrical form ; rising 

 from a more or less distinct hypothallus. Columella reaching to 

 half the height, or nearly to the apex of the sporangium, branch- 

 ing above and continued into the capillitium. Capillitium a more 

 or less dense tangle of purplish-brown, threads, springing from all 

 parts of the columella, anastomosing and branching in semi- 

 circular curves; of nearly equal thickness throughout, the 

 ultimate branches looped, showing few free ends, but connected 



