THE FUNGI WHICH CAUSE PLANT DISEASE 223 



Mouths of the perithecia laterally 



compressed 8. Lophiostomataceae. 



Perithecia without a stroma, and sunken in 

 the substratum, or with a stroma 

 Stromata none; perithecia rarely united 

 above by a black tissue (cls^peus) 

 Asci not thickened at the apex, mostly 

 projecting at maturity 

 Walls of the perithecium thin, cori- 

 aceous; mouth mostly short or 

 plane 

 Asci clinging together in fascicles, [p. 235. 



without paraphyses 9. Mycosphserellacese, 



Asci not fasciculate; with para- 

 physes 10. Pleosporacese, p. 250. 



Walls of the perithecia carbonous or 

 thick coriaceous; spores large, 



mostly enveloped by gelatine. . 11. Massariacese, p. 262. 

 Asci usually thickened apically, open- 

 ing by a pore; perithecia usually 

 beaked 



Perithecia without a clypeus 12. Gnomoniacese, p. 263. 



Perithecia with a clypeus 13. Clypeosphseriacese, 



Perithecia firmly imbedded in a stroma, p. 276. 



the mouths only projecting, or becom- 

 ing free by the breaking away of the 

 outer stromatic layers 

 Stromata fused with the substratum 



Conidia produced in pycnidia 14. Valsacese, p. 277. 



Conidia developed from a flattened 



surface 15. Melanconidaces, 



Stromata formed almost wholly of hard- p. 279. 

 ened fungal hyphae 

 Spores small, cylindric, 1-celled, 

 mostly curved, hyaline or yel- 

 lowish-brown 16. Diatrypaceae, p. 281. 



Spores rather large, 1 to many-celled, 

 hyaline or brown, conidia mostly 



in cavities in the stroma 17. Melogrammatacese, 



Spores 1-celled, rarely 2-celled, p. 282. 



blackish-brown. Conidia devel- 



