CHARACTERS OF MUSHROOMS. 



301 



of the pileus, radiating from the stem to the margin. When the 

 pileus is cut in halves the general outline of the gills may be observed. 

 In outline they may be broad, narrow, lanceolate, triangular, etc. 

 In respect to their ends they are attenuate when gradually narrowed 

 to a sharp point, acute when they end in a sharp angle, and obtuse 

 when the ends are rounded. Again, the gills diXe arcuate ^hen they 

 arch from the stem to the edge of the pileus, and ventricose when 

 they are bellied out vertically toward the earth. 



Figure 244. 



Clitocybe infundibuliformis, pileus in 



fundibuliforni, gills decurrent. 



Figure 245. 



Mycena galericulata, pileus conic to 



campanulate, gills decurrent by a 



tooth, stem fistulose. 



The terms given above are often used in descriptive works, but 

 the most important feature to be noted in the section of the plant is 

 the relation of the gills to the stem. This relation is represented by 

 several distinct types which are sometimes used to limit genera or 

 sub-genera, since the mode of attachment is usually constant in all 

 species of a group. The principal relations of the gills to the stem 

 are described as follows : Adnate when they reach the stem and are 

 set squarely against it (Fig. 247) ; decurrent when they run down 

 the stem (Fig. 244); sinuate or emarginate when they have a notch or 

 vertical curve at the posterior end (Fig. 246) ; and free when they 



