North American species of Mycena.

EXCLUDED AND DOUBTFUL SPECIES

485

"Type collected on humus on the ground in a virgin forest near
Seattle, Washington, October 20-November 1, 1911. W. A. Murrill
223 (herb. N. Y. Bot. Gard.).
"Distribution: Known only from the type locality."
The type is well preserved, and its microscopic characters were
easily obtained. The spores are 4-5 X 9.5-3 u, nonamyloid, and
borne on four-spored basidia. Pleurocystidia and cheilocystidia are
abundant. Those on the sides are 62-85 X 10-16, and somewhat
fusoid-ventricose, with long necks and obtuse apices. The cheilocystidia are shorter and fatter but also of the fusoid-ventricose type.
Both the gill trama and the pileus trama are yellowish in iodine, and
the latter is homogeneous beneath a palisade of pyriform cells. Numerous long pilocystidia (150 u or more) project from this layer.
These are thin-walled, hyaline, and ventricose at the bases. Caulocystidia are numerous over the stipe. They are less ventricose than
the pilocystidia and appear more like hyaline setae with slightly
thickened walls.
Without a doubt M. myceliosa is synonymous with Collybia albipilata. For an account of the latter and illustrations of the microscopic characters see Smith (1938). There is only one discrepancy
in the microscopic details, and that is not important. In Peck's type
the palisade of cells over the cap turned brown in iodine. In Murrill's
type they remained pale yellowish or nearly hyaline. I have not
found such differences as this to be reliable in other Collybiae. Murrill's description also bears out my conclusion in regard to the identity
of his species. The narrow crowded gills, convex gray to whitish
pileus, and long, slender mycelioid stipe are very convincing. He
described the stipe as glabrous, it is true, but the large caulocystidia
of the type clearly demonstrate that his description is in error. The
mycelium around the base of the stipe is white at first but soon becomes tawny. The fungus frequently appears to be growing on
humus but, if one digs far enough, he can usually find the old cone
to which the stipe is attached. Because the fruiting bodies are tough
and revive well, one might at first think they belonged in Marasmius.
Mycena Marasmius Murrill, Bull. Torr. Bot. Club, 67: 154. 1940.
Prunulus Marasmius Murrill, ibid., 148. 1940.
"Pileus convex to expanded, slightly umbilicate at times, densely
cespitose, about 1-1.5 cm. broad; surface dry, smooth, glabrous,