4 
GEORGE F. ATKINSON 
pileus did not yellow to the touch, perhaps due to the fact that the 
plant was collected young and then kept for a few days under un- 
natural conditions. The flesh of the stem was not yellow at the base 
which is said to be a character of Ag. xanthodermus . There was a 
slight odor of almonds, which is present, however, in several species 
of Agaricus. 
This forest form described above (no. 21054 of collections) 
is quite different in appearance from the robust form which occurs in 
pastures in the Jura Mountains. It is almost impossible to obtain 
full grown forms of these robust specimens in the vicinity of Pontarlier, 
since they are much prized as edibles and the localities where they are 
known to occur are visited almost every day by collectors who take 
them in the young stage soon after their emergence from the ground. 
On a hillside of a pasture northeast of Pontarlier there is a large arc 
of a fairy ring which is probably several centuries old. If the circle 
of this arc were completed its diameter would be several kilometers. 
M. August Dornier, of Pontarlier, in whose house I lived during my 
stay in 19 10, informed me that during the past 25 years he had col- 
lected Agaricus arvensis each year from this same arc of a fairy ring. 
It is a long arc with a slight but gradual curvature, and is quite con- 
spicuous on the hillside because of the dark green color of the grass. 
I collected several young plants from this ring on August 8, 1910. 
They were quite robust and were just beginning to expand. They 
were carried to my room, transplanted into pots of earth, covered 
with a bell jar and photographed August 10 and 11. The removal 
from the earth checked their development. 
Although they opened so that fair photographs were obtained, the 
plants did not reach their full size. Notwithstanding this, the pileus 
of the largest measured 12 cm. in diameter and the stems 3-5 cm. 
thick. The pileus was white, then gray and very scaly at maturity 
with fibrous appressed scales, many of them upturned toward the 
margin. Bruises of the surface of pileus and stem change slightly 
to yellow or pale saffron. The veil is large, thick, very floccose 
below and radiately split into coarse scales toward the margin, those 
on the edge being tinged with gray. The stem is smooth above the 
annulus but very scaly below, with larger conic scales crowded near 
the base and often in concentric rings. In age these large scales 
become dull pale brown, while upward they grade into smaller and 
lighter colored ones, the uppermost, next the annulus being floccose 
