PYRENOMYCETES 283 



Perithecia scattered, not in a stroma, subsuperficial, 

 blackish, membranaceous or carbonaceous, much flattened, 

 formed of radiating hyphae ; ostiolum present or absent. 



Microthyrieae. 



Ostiolum or mouth, when present, distinctly elongated. 



Perithecia scattered, not in a stroma, subsuperficial or 

 at first covered by the epidermis, carbonaceous, ostiolum 

 formed of two elongated lip-like ridges, with a very narrow 

 crack through which the spores escape. Lophiostomeae. 



Perithecia scattered, not in a stroma, erumpent, becom- 

 ing superficial, coriaceous or carbonaceous, generally 

 blackish, elongated, sometimes standing up on edge, 

 ostiolum elongated, the entire length of the perithecium, 

 bounded by lip-like ridges on either side, Hysterieae. 



Ascophore irregularly globose, subterranean or rarely 

 almost on the surface of the ground, indehiscent, fleshy. 



Tuberaceae. 



Stroma minute, wart-like ; cavities or loculi minute, 

 numerous, containing one ascus each; asci subglobose, 

 8-spored. Phymatosphaerieae. 



Perisporieae 



Perithecia membranaceous, or in some forms rigid and 

 carbonaceous, produced singly, completely closed, spores 

 liberated on the decay or rupture of the wall. Conidial 

 forms not unusual. Mostly growing on living plants, many 

 of the species being amongst the most destructive of fungus 

 parasites. On account of the closed perithecia the present 



