North American species of Mycena.

EUMYCENA: TYPICAE

(Prunus serotina) log; September 9, 1940, Ann Arbor, Michigan.
Known only from the type locality.
Observations.-Although the species has been found but once,
I have no hesitation in describing it. Its characters separate it
sharply from any other known Mycena. The white to pale-pink
color, hyaline watery juice, crenate margin of the pileus, cespitose
habit, fusoid cheilocystidia, and pink gills at maturity are very distinctive. In general bearing it is very similar to M. haematopus,
but can hardly be considered a white form of it. Many of the carpophores, which were perfectly fresh when collected, had developed
under very favorable weather conditions. The old pilei were infected with a species of Spinellus, a very common occurrence in
Mycenae. The presence of a hyaline watery juice in the stipe excludes the possibility that M. incarnatifolia is an aberrant form of
M. haematopus. Both species were found on the same cherry log.
Mycena incarnatifolia appears to be more closely related to M. rubrotincta. It is readily distinguished, however, by its more aciculate
cystidia, the paler color throughout its development, the pink gills,
and the white stipe, which does not become darker at the base in age.
It is much more brittle than M. laevigata, and its gills are not so
broadly adnate. In fact, carpophores of M. incarnatifolia are almost
waxy in consistency. The white form which Ricken mentions under
his M. polygramma may be the same as M. incarnatifolia. Ricken's
figure (P1. 111, fig. 7) of M. polygramma appears to me to represent
some other species; which one, I am not prepared to say.
155. MYCENA COLLYBIIFORMIS Murrill
Mycologia, 8: 220. 1916
Prunulus collybiiformis Murrill, North Am. Flora, 9: 335. 1916.
Illustration: Text fig. 40, no. 3.
"Pileus thin, rather tough, convex to expanded and at length
umbilicate or depressed, cespitose, 2-4 cm. broad; surface dry, glabrous, cinereous, darker and rugose on the disk; margin entire, pallid,
becoming slightly striate with age or on drying: lamellae adnate,
plane, white, distant, rather narrow, interveined: spores ellipsoid,
smooth, hyaline, 6-7 X 4-5,u: stipe cylindric, somewhat enlarged
at the base, hollow, smooth, pallid, subglabrous, whitish-mycelioid
at the base, 3-5 cm. long, 2-5 mm. thick.
"Type collected on an oak stump at Port Jefferson, Long Island,