COMATRICHA 



155 



1. C. nigra 



2. C. Suksdorfii 



3. C. laxa 



4. C. rubens 



This genus differs from Stemonitis by the absence of a defined, 

 even surface-net, although intermediate forms occur. Globose 

 members differ also by the shape of the sporangia, as there are no 

 globose forms in Stemonitis. 



Sporangia usually globose, or nearly so (also cylindrical 

 in C. Suksdorfii). 

 Columella extending into the sporangium, with the 

 capillitium attached to all parts. 

 Capillitium with threads of even thickness, densely 



netted; sporangia brown. 

 Similar to C. nigra, but sporangia dark, almost 



black, scattered (also cylindrical forms). 

 Similar to C. nigra, but capillitium open. 

 Capillitium with stouter primary branches, the 

 lower branchlets attached also to the persistent 

 base of the sporangial wall; sporangia pale, on 

 leaves. 

 Columella extending into the sporangium, with the 

 capillitium springing only from the upper part. 

 Columella dividing into stout branches; capil- 

 litium springing from the upper part; sporangia 

 on leaves. 

 Capillitium a scanty tuft of slender threads spring- 

 ing from the summit of the columella; sporangia 

 very small, on wood. 

 Columella or stalk merging into the capillitium. 

 Stalk black, dividing into the primary branches 

 of the capillitium; otherwise similar to C. nigra. 

 Sporangia very small; stalk reddish or yellowish 

 brown. 

 Columella absent; capillitium springing directly from 

 the top of the stalk, elastic and expanding. 

 Sporangia usually more or less cylindrical or obovoid. 

 Spores warted or spinulose. 

 Sporangia purplish brown. 



Sporangia 4 to 9 mm. tall; stalks one half the 



total height; spores uniformly warted. 

 Sporangia 2 to 3 mm. tall; stalks one quarter 



the total height; spores uniformly warted. 

 Sporangia 2 to 4 mm. tall; stalks about one 

 half the total height; spores marked with 

 3 to 5 large, dark, warts on the hemisphere. 

 Sporangia pale, lilac-brown. 



Sporangia usually inversely obovoid; cylindri- 

 cal and darker in vars. fusciim and gracilis. 

 Sporangia cylindrical, pale with a pale capil- 

 litium. 

 Sporangia dark, almost black, crowded. 



5. C. lurida 



6. C. fimbriate 



7. C. elegans 



8. C. cornea 



9. C. extendens 



10. C. aequalis 



11. C. subcaespitosa 



12. C. typhoides 



13. C. pulchella 



14. C. tenerrima 



15. C. irregularis 



