North American species of Mycena.

84 NORTH AMERICAN SPECIES OF MYCENA

branaceous, snow white and under a lens appearing as if frosted,
surface moist but hardly translucent, usually distantly sulcate-striate
and the surface somewhat rugose, no odor or taste; lamellae distant,
6-11 reach the stipe, narrow, one tier of lamellulae or none present,
arcuate-adnate to subdecurrent, snow white, pruinose under a lens
-especially along the edges; stipe 10-15 mm. long, filiform, hyaline
watery white, under a lens faintly pruinose, inserted on old leaves by
an equal, perfectly naked base.
Spores 9-12 X 2.5-3 yu, almost aciculate, smooth, hyaline, nonamyloid (tested a few days after drying); basidia four-spored; pleurocystidia similar to cheilocystidia, rare to scattered; cheilocystidia
abundant, 26-32 X 5-8 u, smooth, hyaline, subfusoid to subclavate,
the upper portion only very slightly constricted and the apices obtuse;
gill trama not distinctive; pileus trama homogeneous beneath a welldifferentiated pellicle from which numerous pilocystidia project, the
latter similar in outline to the cheilocystidia or a bit more irregular;
caulocystidia present, similar to the cheilocystidia or more elongated
and irregular.
Habit, habitat, and distribution.-Scattered to gregarious on fallen
beech leaves; November 5, 1940, Milford, Michigan. The species
was very widespread in one woods on November 5, but was not
present in great quantity.
Material studied.-Smith, 15531.
Observations.-This species differs from M. paucilamellata in its
narrow cystidia on the gills, cap, and stipe and in its well-formed
lamellae. I hesitate to emphasize the nonamyloid character of the
spores of M. filiformis because the tests made soon after the specimens
were dried and again at the time this manuscript was completed were
both inconclusive. M. albicolor is distinguished by its smaller spores,
slightly different cystidia, and its habitat on cedar twigs instead of
beech leaves. Many species seem to go from oak to pine without
much difficulty, but the fungi that inhabit the wood and debris of
cedar seem to be more restricted to their habitat than those inhabiting
the wood and debris of other conifers. Thus the difference in habitat
in this instance is considered significant.
19. Mycena albissima, sp. nov.
Illustrations: Text fig. 6, nos. 1-4.
Pileus 4-9 mm. latus, convexus demum subplanus, pruinosus,
glaber, candidus; lamellae latae, distantes, late adnatae vel sub