North American species of Mycena.

EUMYCENA: TYPICAE

303

fragile specimens are sometimes found. Although these have the
appearance of an ordinary gray Mycena, they can readily be identified by the peculiar cystidia. No other Mycena is known to have
greatly elongated pleurocystidia with echinulate apices. The fungus
is apparently limited to conifer wood or debris. It appears to be
most closely related to the species in this group. In stature, consistency, and habit it is almost identical with M. niveipes.
148. MYCENA EXCISA (Lasch) Gillet
Les Hymen., p. 275. 1874
Agaricus excisus Lasch, Linnaea, 4: 534. 1829.
Illustrations:
Text fig. 36, nos. 1-4 (p. 304.)
Beardslee and Coker, Journ. Elisha Mitchell Sci. Soc., 40, pl. 20 (lower
figures).
Fries, Icon. Sel. Hymen., 1, pl. 81, fig. 1.
Pileus 15-35 mm. broad, broadly conic to obtusely campanulate,
the margin sometimes incurved at first, becoming broadly umbonate
to nearly flat, surface densely pruinose at first and appearing dry,
soon polished and moister, "fuscous" (blackish) on the disc, margin
paler and tinged with brown, fading slowly to dark gray or sordid
grayish brown in age, margin entire, opaque when moist, sometimes
very faintly translucent, becoming radially rugulose at maturity;
flesh thin, tough and cartilaginous, grayish brown, no odor or taste;
lamellae broadly and deeply adnexed, in age ventricose and broad,
subdistant to close, white, becoming faintly fuscous or grayish,
edges white or grayish; stipe 3-5 cm. long, 2-3 mm. thick, short,
cartilaginous and tough, equal, hollow, pale fuscous below, pallid
above, evenly white-pruinose at first, polished in age, often compressed and twisted.
Spores 8-10 (12) X 6-7 u, broadly ellipsoid, smooth, amyloid;
basidia four-spored; pleurocystidia scattered to abundant, 50-70 X
10-15 M, fusoid-ventricose with obtuse apices or subcylindric, smooth,
or with an occasional hump or obtuse projection on the elongated
portion, rarely clavate and with several fingerlike prolongations;
cheilocystidia similar to pleurocystidia or clavate and with obtuse
projections or fingerlike prolongations, 35-46 X 10-14 1.; gill trama
homogeneous, vinaceous brown in iodine; pileus trama with a thin
adnate pellicle (when revived in KOH the pellicle distinctly gelati