North American species of Mycena.

246 NORTH AMERICAN SPECIES OF MYCENA

opaque when faded and then often with a stannous sheen, sometimes
whitish and canescent when faded, at other times dull lead color over
all, including the extreme margin, margin sometimes splitting radially
or becoming slightly crenate; flesh thickish under the disc but tapering
abruptly and thin over the remainder of the pileus, grayish, odor and
taste not distinctive; lamellae ascending-adnate, close to subdistant,
narrow but sometimes slightly ventricose, at maturity pale or dark
gray with a pallid margin; stipe 3-8 cm. long, 1-4 mm. thick, hollow,
terete or compressed, fragile, equal or nearly so, glabrous except for
the white-strigose base, apex pruinose at first, glabrous, watery and
translucent, or opaque and then frequently twisted-striate (particularly in forms with compressed stipes), dark to light gray, usually
more or less concolorous with the pileus, the apex usually pallid.
Spores 8-11 X 5-6 (7),', broadly ellipsoid to subovoid, smooth,
amyloid' basidia usually four-spored (two-spored forms are known);
pleurocystidia rare to scattered, sometimes hard to find, fusoidventricose or with one to several short or long obtuse protuberances
over the part which projects, 36-64 X 9-16 u; cheilocystidia similar
but more inclined to have obtuse projections over the enlarged portion; gill trama vinaceous brown in iodine; pileus trama with a thin
pellicle, a well-differentiated hypoderm; and the remainder of broad
hyphae loosely interwoven, all but the pellicle vinaceous brown in
iodine.
Habit, habitat, and distribution.-Gregarious on humus in hardwood and coniferous forests; very abundant during cool, wet fall
seasons throughout the United States and Canada. I have examined
material from New York, Michigan, Colorado, Idaho, Washington,
Oregon, and California in the United States and from Ontario and
Manitoba in Canada.
Material studied.-Smith, 32-596, 32-655, 33-764, 33-1137, 1750,
3547, 3719, 3833, 3844, 3935, 4377, 6160, 6162, 6163, 6280, 7742, 7754,
7779, 8177, 90712, 9185, 9254, 14470, 15033, 16232, 18139. Beausignour, November 29, 1935. Bisby, September 27, 1933, and
November 29, 1935, Manitoba, Canada. Mains, 5221. Overholts,
1992. Slipp: UIFP, 3042.
Observations.-Previously I considered M. aetites and M. murina
distinct species. Continued studies have convinced me that these
are merely variations of one species, for which I am recognizing the
name M. stannea instead of M. aetites. Ktihner used the latter name
and included the North American material under it. However, cer