48 FUNGUS-FLORA. 



teeth, which remain as a border surrounding the disc ; when 

 the ascophore is elongated, dehiscence takes place by a slit 

 running its entire length, in both cases the disc is quite 

 exposed when moist, by the gaping of the lips, and in this 

 respect differ from the Hysteriaceae, where the usually rigid, 

 carbonaceous lips of the excipulum remain almost closed at 

 maturity. 



In the majority of species the ascophores are scattered, but 

 in Rhytisma and one or two other genera they are gregarious 

 on an effused, black stroma. 



The species mostly occur on leaves or the stems of herba- 

 ceous plants ; a few, as SchizotJiyrium and Rhytisma, are 

 parasites, but the majority are saprophytes. 



ANALYSIS OF THE GENERA. 

 A. AscopJiores scattered, splitting above in a radiate manner. 



Keithia. Spores brown. 



Coccomyces. Spores arranged in a parallel fascicle in 

 the ascus, needle-shaped. 



Coccophacidium. Spores arranged in a parallel fascicle 

 in the ascus, narrowly fusiform, the widest part above 

 the middle of the spore. 



Schizothyrium. Spores elliptical, 1-septate. 



Phacidium. Spores narrowly elliptical, 2-seriate; hypo- 

 thecium pale, thin. 



Trochila. Spores narrowly elliptical, 2-seriate; hypo- 

 thecium firm, blackish. 



B. Ascopliores scattered, elongated, opening by a long, gaping 

 slit. 



Colpoma. Spores long and slender; arranged in a 

 parallel fascicle in the escus. 



Xylographa. Spores elliptical, continuous, 2-seriate. 

 Pseudographis. Spores muriform. 



