North American species of Mycena.

398 NORTH AMERICAN SPECIES OF MYCENA

The pileus trama is homogeneous, nonamyloid, and somewhat
"glassy" or subgelatinous when revived in KOH. The surface is
covered with a loose or tangled mass of hyaline clavate pilocystidia
measuring 7-11 X 15-96 j. The gill trama is nonamyloid and appears to be slightly gelatinous in KOH. The basidia are four-spored.
Pleurocystidia are absent, but cheilocystidia are abundant; they
measure 26-52 X 9-14, and are narrowly clavate to subeylindric.
Their walls, which are thin, collapse readily. The relationships of the
species are as pointed out above by Murrill.
202. Mycena umbrina, sp. nov.
Illustrations: Text fig. 49, nos. 1-4.
Pileus aquosus, 3-5 mm. latus, convexus, umbrinus, impolitus;
lamellae distantes, decurrentes, angustae, pallide griseae; stipes 18 -20 mm. longus, 1 mm. crassus, aequalis, aquosus, subumbrinus;
sporae 7-9 X 4.5-6,, amyloideae. Specimen typicum in Herb.
Univ. Mich. conservatum. Legit A. H. Smith, n. 33-538, prope Rock
River, Mich. June 17, 1933.
Pileus 3-5 mm. broad, convex, in age broadly convex but hardly
depressed, dark blackish brown over all, with blackish striations,
margin becoming slightly paler in age, surface unpolished to subtomentose, moist, subhygrophanous; flesh dark brown, thin, very
watery, no odor, taste not recorded; lamellae distant, arcuate-decurrent, narrow, pale gray, edges even; stipe 18-20 mm. long, 1 mm.
thick, equal, watery, and very fragile, smoky gray over all or pallid
near the apex, pruinose.
Spores 7-9 X 4.5-6 u, subovoid, amyloid (reaction strong),
smooth; basidia four-spored; pleurocystidia and cheilocystidia not
differentiated, gill trama homogeneous, some lactifers present, yellowish in iodine; pileus trama corticated, with a very compact layer
of clavate to subfusoid pilocystidia (as in M. marginella), irregularly
arranged, their contents dark brown, beneath this a region of broad
hyphae with elongated cells also with dark-brown contents, remainder
floccose, not amyloid in any part; clavate caulocystidia scattered
over the apex of stipe, their contents also dark-colored (cystidia on
cap and stipe 26-58 X 8-18 u).
Habit, habitat, and distribution.-Single in a bed of moss; Rock
River, A. H. Smith, 33-538, June 17, 1933, Michigan. Known only
from the type collection.