546 POUL LARSEN 
at first coloured like the cap, then more tawny, edge dentate. — Basidia 
clavate, 4-spored. — Spores tawny, spherical or broadly ellipsoidal, 
echinulate, the smallest 5X5 u, the mediumsized 6.5X5—6 u and the 
largest 7.5X5.5—6 u. — No cystidia. 
Allied to C. nidulans (Pers.) Quélet, yet easy to distinguish both 
macro- and microscopically. 
Psalliota Fries. 
563. P. campestris (Linné) sensu J. E. Lange, Dansk Botanisk Arkiv, 
vol. 4, No.12, p. 9. 
Vallanes in Lagerfljöt [P. L.). — In manured homefields. 
Cap at first hemispherical with incurved margin, then expanded, 
convex with straight margin, flesh thick, reddening faintly when broken, 
surface silky and white. — Stipe subcylindrical, stuffed, surface like that 
of the cap, bearing an evanescent ring splitting up into hairs. — Gills 
free, at first pale, then red, at length dark brown. — Spores somewhat 
irregularly ovoid, smooth, purple brown, 6.5—8%*4.5—5 u. 
Note. Several other localities have been recorded by collectors, 
though it has not been possible to ascertain what they meant by P. 
campestris, viz. Grimsey [O. D.], heaths by Grjötnes and Akureyri [C. H. O.], 
Mööruvellir [St. St., Vallanes [Helgi Jönsson). 
564. P. Elvensis Berkeley et Broome var. alba n. var. 
By Laxä south-west of Myvatn [P.L.]. — On mounds of earth round 
sheepfolds. 
Pileus 7—14 cm broad, campanulate with incurved margin, white 
or dingy white, cuticle thick, splitting up into patches ending with de- 
flexed and upward curving points, flesh thick, white, reddening faintly 
when bruised, with a yellow tinge below the cuticle. — Stipe subcylin- 
drical but with the base attenuated, fistulose, filled below with a felty 
pith; flesh of stipe like that of cap, but citron-yellow in the lower part. 
Ring raised, skin-like, single. — Gills at first pale, then incarnate (m 3), 
finally dark reddish brown (c 3), up to 12 mm broad, crowded, rounded 
towards the stipe, free. — Basidia 4-spored. — Spores spherical or broadly 
ellipsoidal, the spherical spores are 6 « in diameter, the ellipsoidal ones 
7—7.5X6 u. Differing especially in the colour of the pileus. 
565. P. arvensis (Schaeffer) sensu Ricken. 
Agaricus arvensis Schaeffer, Fung. Ic., t.310 and 311. 
Reykjahliö near Myvatn [P.L.]. — Under scattered birches on lava fields. 
Pileus 7—10 cm broad, convex, then plano-convex, silkyhaired or 
squamulose, white to whitish yellow; flesh white, assumes a yellow tinge 
when bruised. — Stipe cylindrical, bulbous, hollow, white, at length 
becoming sooty, bearing a double ring, the lower layer radiately rimose. 
— Gills at first almost white, becoming greyish red and finally almost 
black, broadest in front, free. Basidia 4-spored. — Spores ellipsoidal, 
smooth, purple brown, 7—7.5% 4—4.5 u. 
