102 



scribed as new some twenty-seven species. In the following key 

 a synopsis is given of seventy-seven species and varieties that 

 have been reported from North America. It is probable that 

 some species have been omitted, since the literature has not yet 

 been exhaustively examined, and in some cases species are 

 doubtless referred to the wrong section owing to imperfect de- 

 scriptions. Any further notes or any corrections will be thank- 

 fully received by the writer. 



Key to the Sections of the Genus 



i. Lamellae equal ; pileus with a separable pellicle. Sec. 5, Fragiles. 



Lamellae unequal, heterophyllous ; pellicle adnate or none. 2. 



2. Margin of pileus conspicuously striate. Sec. 4, Heterophyllae. 

 Margin of pileus even, not striate. 3. 



3. Pileus dry from the first, cuticle breaking areolately, 



scaly, pruinose, etc. Sec. 3, Rigidae. 



Pileus moist or viscid, smooth, cuticle not breaking. 4. 



4. Lamellae conspicuously forking, slightly heterophyllous. 



Sec. 2, Furcatae. 

 Lamellae conspicuously heterophyllous, seldom forking. 



Sec. 1, Compactae. 



Key to the North American Species 



Section i, Compactae 



1. Pileus white or pallid. 2. 

 Pileus cream-color or tinted. 3. 

 Pileus brown or fuliginous ; lamellae darkening or drying. 4. 



2. Lamellae distant ; stipe 2-6 cm. R. delica Fr. 

 Lamellae crowded ; stipe 1-2 cm. R. brevipes Pk. 



3. Lamellae and flesh changing to brown when wounded. R. compacta Frost. 

 Lamellae and flesh unchanging. R. cremoricolor Earle. 



4. Lamellae and flesh changing to reddish when wounded. R. nigricans (Bull.) Fr. 

 Lamellae and flesh unchanging. R. adusta (Pers. ) Fr. 



Section 2, Furcatae 



1. Pileus white, pallid or slightly tinted. 2. 

 Pileus greenish or brownish green or olivaceous. 3. 

 Pileus some shade of red, at least when young. 6. 



2. Flesh blackening when wounded. R. sordida Pk. 

 Flesh white, not blackening. R. basifurcata Pk. 



3. Stipe brighter green than pileus. R. viridipes Bann & Pk. 

 Stipe white or whitish. 4. 



