HYMENOMYCETES 361 



systematic standpoint, and constitutes a most important 

 generic character. 



In the simpler types the gills run down the stem for 

 some considerable distance, when they are described as 

 decurrent ; when the gills are attached to the stem by their 

 entire width, they are said to be adnate ; when cut out or 

 rounded behind, so that onlya portion of the width of 

 the gill is attached to the stem, the term adnexed is 

 used; whereas, when the gills are rounded off behind, 

 so that they terminate before reaching the stem, they are 

 said to be free ; meaning free from the stem. 



In the primitive types of the Agaricineae, illustrated by 

 species belonging to the genera Cantharellus, Pleurotus, 

 Trogia,) etc., the sporophore is resupinate, that is, the 

 imperfectly evolved pileus is in contact with the matrix, 

 and the gills or hymenium uppermost. In such species 

 the gills are rudimentary in structure, and often more 

 resemble wrinkles or folds than gills as understood in the 

 higher forms, and agree closely with the rugulose appear- 

 ance of the hymenium in such genera as Cratercllus, 

 belonging to the Thelephorineae, the family from which 

 the Agaricineae descended. A further stage of advance is 

 seen in Lenzites, where the sporophore is attached to the 

 matrix by a broad base, and the hymenium has become 

 inferior. Following this is the dimidiate, flabellate, or semi- 

 circular pileus supported by a lateral stem, that is, a stem 

 springing from the margin of the pileus. This type leads 

 by degrees to the highest phase of sporophore develop- 

 ment attained to by the Agaricineae, a pileus bearing the 

 hymenium on its lower surface, and supported by a central 

 stem. Even in this highest stage of development there 

 are marked differences of degree. In the simplest stage 



