246 



THE ASCOMYCETES 



the Inoperculates. In the first, the asci open by means of a Hd 

 or, more rarely, a transverse slit; in the second, no special mecha- 

 nism for dehiscence of the asci is provided. Seaver (1928, 1942) 

 monographed the Operculates and included therein the Pezizales, 

 which embrace the two famihes, Pezizaceae and Elvellaceae (Hel- 

 vellaceae). The Pezizaceae contain the cup-shaped or discoid 



Peridium Paraphyses 



Ascogonium 



Ascogenous 

 hyphae 



Antheridium 



Fig. 97. Fyronevm confliiens. A. Cluster of paired oogonia and antheridia. 

 B. Multinucleate oogonium, antheridium, and trichogyne. C. Diagram- 

 matic representation of parts of ascocarp of P. confitieiis. 



forms; and Elvellaceae, the pileate ones. Nannfeldt (1932) mono- 

 graphed the Inoperculates, including two orders, Ostropales and 

 the Helotiales. In Nannfeldt's arrangement the Ostropales con- 

 tain a single family, Ostropaceae, and the Helotiales contain the 

 Dermateaceae, Phacidiaceae, Orbiliaceae, Hyalocyphaceae, Helo- 

 tiaceae, and Geoglossaceae. 



The tip of the ascus in the Ostropales is thickened and is pierced 

 by a narrow canal. The ascospores are filamentous and readily 

 fall apart into cvHndrical elements, whereas those of the Helo- 

 tiales are never filamentous and do not break up into cylindrical 

 cells. 



