5 (3) Ascospores broadly ellipsoidal or ovoid; 10-15 /j in dia- 

 meter Nais inornata 



6 (2) Ascospores exclusively 2-celled 7 



6 (2) Ascospores 2- to 4-celled . . . (see also Phragmosporae) Leptosphaeria {p. 29) 



7 (6) Ascospore wall verruculose Didymosphaeria {p. 23) 



7 (6) Ascospore wall smooth 8 



8 (7) Ascospores predominantly larger than 33 /u 9 



8 ( 7) Ascospores usually smaller than 33 ^ 



.10 



9 (8) Ascospore cells unequal in size and shape; lower half cylindrical; upper half pointed 



Didymosphaeria (p. 23) 



9 (8) Ascospore cells equal in size and shape, straight or slightly curved Leptosphaeria (p. 29) 



10 (8) Ascospore 2-celled, usually unequal in size, occasion- 

 ally biturbinate Microthelia linderi 



10 (8) Ascospore more than 2-celled, equal in size Leptosphaeria (p. 29) 



17 



