I32 DISCOMYCETES [CH. 



In Z<Y>/W lubrica a large branching cell, presumably an oogonium, 

 occurs at the base of the very young ascocarp and appears to give rise to 

 the ascogenous hyphae. 



As far as the characters of the mature fruit are concerned, two lines of 

 development can be traced, both starting from Geoglossum and passing, the 

 one through Spathularia to Vibrissea, the other through Mitrula and Leotia 

 to the Helvellaceae. 



In the species of Spathularia and Vibrissea, as in Geoglossum, the spores 

 are very long, narrow and septate, lying side by side in the ascus. Geo- 

 glossum is distinguished by its coloured spores (fig. 92 a), the other two genera, 

 in both of which the spores are hyaline (fig. 92 ), by the form of the 

 fructification. 



In the rest of the Geoglossaceae, as in the Helvellaceae, the spores are 

 elliptical and hyaline, and are arranged one above the other in the ascus. 

 They may be continuous or septate. In Mitrula the fertile region is 

 irregularly club-shaped, and in Leotia pileate. 



A relationship to the Pezizales suggests itself at various points, and 

 perhaps especially through Leotia, to the Helotiaceae and Mollisiaceae where, 

 as in the Geoglossaceae, the ascus opens by a slit or pore from which a plug 

 of wall substance is ejected, not as in the majority of the Helvellales and 

 Pezizales by a definite lid. 



GEOGLOSSACEAE : BIBLIOGRAPHY 



1897 MASSEK, C. A Monograph of the Geoglossaceae. Ann. Eot. xi, p. 225. 



1908 DURAND, E. J. The Geoglossaceae of North America. Ann. Myc. vi, p. 387. 



1910 BROWN, W. H. The Development of the Ascocarp of Leotia. Bot. Gaz. 1, p. 443. 



PHACIDIALES 



In the Phacidiales the ascocarp is immersed in the matrix. It is usually 

 small in size and leathery, waxy, or coriaceous in consistency; an epithecium 

 is often developed. Certain members of the group resemble the Hysteriales 

 in many points and differ from them chiefly in the greater exposure of the 

 fertile disc at maturity. 



There are two chief families. 



Stictaceae 



The Stictaceae constitute a considerable group of small forms, occurring 

 saprophytically on wood or other plant remains. Their development and 

 minute anatomy, apart from systematic characters, is practically uninvesti- 

 gated. They have a fleshy or waxy disc, pale and clear coloured, usually 

 white, yellow, or tinged with pink. The sheath is not always developed, when 

 present it is thin and white and is mealy owing to the presence of particles 



