1919^ Ckaterellus_, Canthakellus and Related Genera 25 



4. Plants not exuding a juice (except from the stems of certain species 



of Mycena) : 5 



5. Plants usually quite brittle, the flesh composed of globular cells; 



spores white, creamy or yellowish, mostly spherical and marked 

 with spicules, warts, or ridges (rarely smooth) Russula 



5. Plants not as above in all respects 6 



6. Gills waxy and semi-translucent in appearance, usually thick and 



broadening towards the cap, the entire plant soft and usually 

 fragile (The gills of Laccaria approach these in appearance, but the 

 plants are tougher and less brittle) Hygrophorus 



6. Gills not as above, or if nearly so then the plant tough and firm 7 



7, Stem none, or, if present, not in the center of the cap (rare excep- 



tions) ; plants mostly growing on wood Pleurotus 



7. Stem central or nearly so 8 



8. Stem easily separating from the cap, both stem and cap fleshy; gills 



free or nearly so 9 



8. Stem continuous with the cap, not easily separating 10 



9. Stem at base furnished with the remains of a volva, such as a cup or 



rings or warts or scales or meal (in a few species where these are 

 regularly or at times absent the stem is distinctly bulbous) ; veil 

 present and usually forming a ring on the stem; gills free or nearly 



so Avianita 



9. Stem and gills as above, but veil (and ring) absent Amanitopsis 



9. Veil present and gills free or nearly so, but stem without remains of 



a volva Lepiota 



10. Stem fleshy or fibrous and elastic, of the same texture as the cap. . . .11 



10. Stem cartilaginous, of a different texture from the cap 14 



11. Stem with a veil (and ring) ; volva wanting; plants densely clustered 



and growing from stumps or roots Arinillaria 



11. Stem without a veil or volva 12 



12. Gills notched at the stem, i. e., attached but not by their whole width, 



and not decurrent 13 



12. Gills decurrent, not sinuate (in a few species the gills are usually not 



decurrent, and they are sometimes various in this respect in the 

 same plant, as in C. tumtilosa. In C. dealbata they are squarely 

 adnate or even a little notched at the stem as in Tricholoma. and in 

 C. nebularis they are usually squarely attached) Clitocybe 



13. Gills thick with blunt edges, purplish or pinkish at all ages, but 



becoming conspicuously dusted by the white spores; stem toughish 

 and fibrous Laccaria 



13. Gills thin, variously colored (if pinkish then turning color when 



bruised or in age) ; stem fleshy TrUholojua 



14. Gills decurrent Omphalia 



14. Gills not decurrent, or barely so 15 



15. Margin of cap inrolled when young Collybia 



15. Margin not inrolled when young, plants small Mycena 



