48 ASCOMYCETES 



2. Walls of the perithecia thin and membranous ; asci soon disappearing. 3. 

 Walls of the perithecia coriaceous or carbonaceous. 4. 



3. Perithecia always superficial, with copious tufts of hair at the mouth. 



Chaetomiaceae. (2 gen.)* 



Perithecia usually sunken, with short hairs about the mouth or none ; 

 growing on manure. Sordariaceae. (7 gen.) 



4. Perithecia either entirely free, or at most with the base slightly sunken 



in the substratum or stromatic layer. 5- 



Perithecia more or less deeply sunken in the substratum at base, free 



above. 8. 



5. Stroma wanting or merely thread-like or tomentose. 6. 

 Stroma present. 7. 



6. Mouths of the perithecia mostly in the form of short papillae. 



Sphaeriaceae. (25 gen.) 

 Mouths of the perithecia more or less elongate, often hair-like. 



Ceratostomaceae. (8 gen. ) 



7. Stroma mostly well developed with an indefinite border ; perithecia in 



close irregular masses, never flask-like nor funnel-like at the apex. 



Cucurbitariaceae. (9 gen.) 



Stroma small, sharply bordered ; perithecia in rows or in regular rounded 

 masses, flask-shaped, with funnel-formed mouths. 



Coryneliaceae. (3 gen.) 



8. Mouths of the perithecia circular in outline. 



Amphisphaeriaceae. (9 gen.) 

 Mouths of the perithecia laterally compressed. 



Lophiostomaceae. (8 gen.) 



9. Asci usually thickened at the apex, breaking open by a pore ; mouths 



of the perithecia mostly beaked (rarely only rounded). 10. 



Asci not thickened at the apex, mostly projecting at maturity. II. 



10. Perithecia with a clypeus. Clypeosphaeriaceae. (8 gen. ) 

 Perithecia without a clypeus. Gnomoniaceae. (10 gen. ) 



11. Walls of the perithecia thin, coriaceous; mouth mostly short or 



plane. 12. 



Walls of the perithecia carbonaceous or thick coriaceous ; spores large, 



mostly enveloped in gelatine. Massariaceae. (10 gen.) 



12. Asci clinging together in fascicles, without paraphyses. 



Mycosphaerellaceae. (12 gen.) 

 Asci not fascicled ; paraphyses present. Pleosporaceae. (23 gen.) 



'' To give some idea of the relative size of the families we have added 

 the number of genera in each in parenthesis. 



