Massee . — A Monograph of the Geoglosseae . 227 
with in the hymenium of the lowest types of the Basidio- 
mycetes, as Hymenochaete , where, as in Geoglossum , the spines 
are rigid and coloured, and project above the general level 
of the hymenium, giving it a velvety appearance, and possibly 
exercising a protective function in preventing the surface of 
the hymenium from being eaten by minute snails, &c., as is 
the case with the unprotected hymenium of the allied genera 
Corticium and Stereum . In Peniophora , a genus closely allied 
to Hymenochaete , the spines are colourless, not so rigid, and 
the surface of the exposed portion when old is usually 
incrusted with particles of oxalate of lime. From this type 
of structure of the spines we pass on by a gradual transition 
to what are known as cystidia ; large, sterile cells of various 
shapes, present in the hymenium of many species of the 
Agaricineae. The primitive spine-like form of structure 
present in Geoglossum also occurs in the simplest known types 
of other groups of Fungi, as the Hydneae, Clavarieae, &c. 
The asci are elongated and narrowly clavate, the apex 
somewhat narrowed, thick-walled, and furnished with an 
apical plug of a substance which becomes coloured clear blue 
when treated with a solution of iodine (Fig. 11). According 
to Boudier’s 1 system of classification, the fleshy Discomycetes 
are divided into two primary groups depending on the mode 
of dehiscence of the asci. The Geoglosseae belong to the 
Inopercules , characterized by the asci opening at the apex by 
a small circular opening having a raised, torn margin, or 
by an elongated slit ; the rupture being effected by the swelling 
of the apical plug that becomes blue with iodine (Fig. 64). 
In the second group, called the Opercules , dehiscence takes 
place in a circumscissile manner, the apex of the ascus 
separating along a clearly defined line, like a lid, which 
either falls completely away, or remains attached by one side, 
looking like an upraised, hinged lid after dehiscence. The 
Ascoboleae are typical examples of the Opercules . 
There are normally eight spores in an ascus ; in the lowest 
1 Bull. Soc. Mycol. France, I, 97, 1885. 
R 
