80S STUDIES OF AMERICAN FUNGI. 



FAMILY AGARICACEAE. 



Pileus more or less expanded, convex, bell-shaped ; stipe central or nearly 

 so ; or the point of attachment lateral, when the stipe may be short or the pileus 

 sessile and shelving. Fruiting surface usually on the under side and exposed 

 toward the earth, lamellate, or prominently folded or veined. Lamella? or gills 

 radiating from the point of attachment of the pileus with the stipe or with the sub- 

 stratum in the sessile forms; lamella? simple or branched, rarely anastomosing 

 behind, clothed externally on both surfaces with the basidia, each of which bears 

 four spores (rarely two), cystidia often present. 



Key to the North American genera. 



THE WHITE-SPORED AGARICS. 



(Sometimes there is a faint tinge of pink or lilac when the spores are in bulk, 

 but the color is not seen under the microscope.) 



Plants soft, fleshy or nearly so, usually soon decaying ; 



dried plants do not revive well when moistened. ... i 

 Plants tough, either fleshy or gelatinous, membranaceous, 



corky or woody, persistent, reviving when moistened. 13 



1 Gills acute on the edge 2 



Edge of the gills obtuse, or gills fold-like, or vein-like, but 



prominent .... 12 



2 Trama of the pileus of interwoven threads, not vesiculose. 3 

 Trama of the pileus vesiculose, plants rigid but quite 



fragile 11 



3 Gills thin, not much broadened toward the pileus 4 



Gills broadened toward the pileus, of waxy consistency. Hygrophorus. . no 

 4 Stipe central or sub-central. (Some species of Pleurotus 



are sub-central, but the gills are usually not decurrent. ) 5 

 Stipe on one side of the pileus, or none, rarely with the 

 stipe sub-central. (Some species of Clitocybe are sub- 

 central.) Pleurotus. . . 102 



5 Stipe fleshy, pileus easily separating from the stipe, gills 



usually free ... 6 



Stipe fleshy or fibrous and elastic, pileus confluent with 



the stipe and of the same texture 7 



Stipe cartilaginous, pileus confluent with the stipe, but of 



a different texture 9 



6 Volva and annulus present on the stipe. . . . Amanita. . 52 



Volva present, annulus wanting Amanitopsis. . 74 



Volva wanting, annulus present. ... . Lepiota. . 77 



7 Annulus and volva wanting 8 



Annulus usually present (sometimes vague), volva want- 

 ing, gills attached to the stipe Armillaria. . 83 



8 Gills sinuate Tricholoma. . . 87 



Gills decurrent, not sinuate . . Clitocybe. . . 89 



9 Gills decurrent, pileus umbilicate . Omphalia. . 100 



Gills not decurrent i 



