PEZIZALES 317 



vessels, extensive formation of special tissues, etc., remind one of the 

 structures of pileate fungi, or of the stems and leaves of cormophytes. 

 An attempt has been made to use the structure of the apothecium for 

 systematic classification of the Pezizales, especially to distinguish funda- 

 mentally between gymnocarpous (exogenous) and angiocarpous (endo- 

 genous) forms and to unite the gymnocarpous forms in the series with 

 the Helvellales and the angiocarpous forms in the Pezizales. Ontogenetic 

 investigations have not supported this conception. On the one hand, 

 many earlier forms considered gymnocarpous, as Helvetia, have been 

 shown hemiangiocarpous; on the other hand, in Ascobolus gymnocarpous 

 and hemiangiocarpous species appear side by side. Besides the vari- 

 ability of the terms gymnocarpous and angiocarpous lead to abstract 

 difficulties; thus in Leotia the sheath is only transitory and disappears 

 before the hymenium is formed. The hymenium is exogenous, as in 

 typical gymnocarpous forms, although the young fructification was 

 surrounded by a hyhal veil. 



Hence one is obliged to unite the earlier order of Helvellales and 

 Pezizales, as is done here with the support of Boudier and Durand. 

 The classification of this large new order is accomplished on the biological 

 individuality of the asci. In one series, the Inoperculatae, the asci open, 

 as in the other Ascomycetes, at their tips by an irregular rupture which 

 may close after the exit of the ascospores and be no longer visible. In 

 another series, the Operculatae, they open by the raising of a pre-formed 

 lid (operculum). In addition to this anatomical feature of the asci, 

 these two series differ in histological characters (Lagarde, 1906), which 

 cannot yet be formulated in general terms. 



The further classification of the two series is based on the structure 

 of the fructifications. Each series is split into a large number of families 

 on characters of the fructification, of which seven will be discussed in 

 the Inoperculatae, and five in the Operculatae. They are parallel in 

 several respects and, in the higher forms, lead to striking convergence 

 phenomena. As very few of the transitional types have been ontogenet- 

 ically investigated, the construction of a family tree is not yet possible. 



The simpler groups of the Inoperculatae, as the Philipsielleae, the 

 Agyrieae, the Celidiaceae and Patellariaceae, are mostly parasitic or 

 saprophytic on wood, bark or lichens, etc. Morphologically they are 

 very close to many lichen-forming Discomycetes and have therefore 

 often been considered lichens. The fructifications are frequently small 

 and transitory and hence generally known only from hebarium material. 

 In any case, they are connected by numerous intermediate forms with the 

 Plectascales, especially the Gymnoascaceae, and with the Myriangiales, 

 especially the Saccardiaceae, so that they are classified variously by 

 systematists. The Philipsielleae and Agyrieae, especially, have entirely 

 atypical immarginate fructifications whose spherical or ovoid asci are 



