COMATRICHA 171 



he included, however, in his list some species which have since been 

 known by his generic name. 



The distinction between the two genera is admittedly somewhat 

 artificial, and species are sometimes arbitrarily assigned to one genus 

 or the other. The diagnosis in any case turns upon the presence or 

 absence of a surface net. In Stemonitis this is formed by the anasto- 

 mosing of the ultimate divisions of the capillitial branches. In Coma- 

 tricha the anastomosing is general, from the columella out, and is not 

 specialized at the surface. Attempts to reunite the two genera seem 

 to result in no apparent advantage. They come very near together, 

 but their separation as suggested by Rostafinski remains convenient. 



KEY TO THE SPECIES OF COMATRICHA 



o. Peridium iridescent, persistent, at least at the base; stipe 



very short or lacking b 



a. Peridium fugacious; stipe distinct d 



b. Sessile or short-stipitate; clavate-truncate; spores 



roughly warted 1 . C. caspitosa 



b. Sessile; cylindrical; spores reticulate c 



c. Black; peridium more or less persistent over entire sur- 

 face; spores 10-12 /z 2. C. cylindrica 



c. Brown; peridium persistent only at base; spores 8-9 ju. . . . 3. C. rispaudii 



d. Sporangia densely clustered jcapillitium scantily branched e 



d. Sporangia gregarious or scattered; capillitium various g 



e. Ferruginous, 5-10 mm. tall 4. C. flaccida 



e. Dark brown or blackish / 



/. Sporangia 10-25 mm. tall; spores roughly warted or 



reticulate 5. C. longa 



f. Sporangia 3-6 mm. tall; spores echinulate 6. C. irregularis 



g. Spores black or dark purplish in mass; violet-brown by 



transmitted light h 



g. Spores lilaceous or ferruginous in mass; pallid by trans- 

 mitted light u 



h. Capillitium simple, with few or no anastomoses i 



h. Capillitium intricate I 



i. Capillitium caducous, falling away with the spiny spores . . 7. C . filamentosa 



i. Capillitium persistent, at least above; spores minutely 



warted or nearly smooth j 



j. Capillitium moderately dense, but with few anastomoses; 



columella nearly reaching the summit 8. C. laxa 



j. Capillitium looser; columella shorter k 



k. Very minute, usually under 0.5 mm. tall; columella not ex- 

 ceeding middle of sporangium; capillitium forking repeatedly 9. C. cornea 



k. Minute, 0.7-1.5 mm. tall; columella very short; capillitium 

 of slender, simple or sparsely branched threads with ex- 

 panded tips 10. C. fimbriata 



I. Spores mostly over 10 n m 



I. Spores mostly under 10 p. n 



