North American species of Mycena.

EUMYCENA: CORTICOLAE

73

reliable characters for this species are the broad arcuate gills, which
develop a distinct decurrent tooth in age, the spores, the habitat, and
the cheilocystidia. The colors are not at all distinctive.
Some might consider this fungus to be more closely related to the
species in the section Omphaliariae than to the others of this section.
It should be remembered, however, that all the Corticolae except
M. subcana are characterized by broadly adnate gills, so that any
relationships determined by that character would also apply to the
others. The group represents an interesting phylogenetic problem.
It can be interpreted either as a line of evolution or as a level of evolution influenced in some measure by the nature of the habitat.
15. Mycena subcana, sp. nov.
Illustrations:
Plate 7 A, C, E; Text fig. 4, nos. 1-2 (p. 74).
Smith, Mycologia, 29, 353, fig. 3, b (as M. brevipes).
Pileus (0.5) 1-2.5 (3) cm. latus, demum campanulatus vel convexus, pruinosus, persistens subcanus, fuligineus demum cinereus,
striatus; lamellae adnatae, angustae, vel sublatae, subdistantes vel
distantes, pallidae; stipes 1.5-3.5 cm. longus, 1.5-3 mm. crassus,
aequalis vel subbulbosus, pallide fuligineus, pruinosus, basi strigosus;
sporae (7) 8-10 X 5-6, late ellipsoideae; cheilocystidia (30) 40-64 X
10-18/u, fusoide ventricosa vel subclavata. Specimen typicum in
Herb. Univ. Mich. conservatum. Legit A. H. Smith, n. 8752,
Siskiyou National Forest, Calif., Nov. 15, 1937.
Pileus (0.5) 1-2.5 (3) cm. broad, ovoid when young, the margin
straight, expanding to obtusely conic, campanulate or convex, hoarypruinose when young, becoming naked but retaining a somewhat
hoary appearance at maturity, glabrous, moist, hygrophanous, translucent-striate almost to the disc, "deep neutral gray" and fading to
"pale neutral gray" on the disc, sometimes "pale drab gray" over all,
the margin usually "pallid neutral gray" and radially rugulose (dark
ashy gray on the disc with a paler ashy-gray margin and fading to pale
ash-gray over all), flesh thin, fragile, pallid gray, not changing when
bruised, odor and taste not distinctive; lamellae adnate, narrow to
moderately broad, subdistant to distant at maturity, intervenose at
times, whitish to pale cinereus, edge concolorous with the sides and
even; stipe 1.5-3.5 cm. long, 1.5-3 mm. thick, equal or the base subbulbous, concolorous with the pileus, pale cinereous or nearly white,