North American species of Mycena.

EUM YCENA: OMPHALIARIAE

basidia four-spored; pleurocystidia scattered to abundant but embedded in the hymenium and easily overlooked, 32-46 X 8-11 u,
smooth, subfusoid, originating deep in the subhymenium, cheilocystidia similar to pleurocystidia or up to 60, in length because of
the long pedicel, projecting 5-15 j; gill edges not gelatinizing; gill
and pileus trama strongly amyloid; pellicle of the pileus gelatinous,
made up of very narrow (2-3,u) smooth hyphae.
Habit, habitat, and distribution.-Gregarious under ponderosa
pine, October and November; Oregon.
Material studied.-Smith, 8925 type, 18113, 18117, 18131.
Observations.-At first sight I mistook this species for a form of
M. clavicularis. The specimens were collected after a heavy rain,
and I thought that the gluten had been washed off the stipe and that
the pellicle of the pileus had gelatinized because of the prolonged wet
weather. A careful study showed, however, that there were no
grounds for such assumptions. The cystidia separate this species
from M. clavicularis. From M. laevigata it differs in both habitat
and cystidia-even if one overlooks the stature and colors. Actually,
the species appears to be most closely related to M. latifolia by its
habit, habitat, consistency, and broadly adnate gills. It differs in
having a thick gelatinous pellicle over the pileus and in its smooth
cheilocystidia. The most satisfactory method of studying the cystidia is first to section and then to crush the sections under a cover
glass just enough to spread the basidia well without destroying the
outline of the gills.
186. Mycena serotina (Peck), comb. nov.
Omphalia serotina Peck, Bull. Torr. Bot. Club, 34: 98. 1907.
Omphalopsis serotina Murrill, North Am. Flora, 9: 314. 1916.
"Pileus submembranous, convex, sometimes slightly depressed
in the center or subumbilicate, widely striate on the margin when
fresh and moist, slightly striate when dry, grayish-brown, grayishwhite or subcinereous; lamellae rather broad, subdistant, adnate or
slightly decurrent, white; stem slender, hollow, glabrous, slightly
villose-tomentose at the base, pallid; spores narrowly elliptic, 8-10 A
long, 4-5 A broad.
"Pileus 1-2 cm. broad; stem 1.5-2.5 cm. long, 1 mm. thick."
Among fallen leaves in woods; the type locality is near Boston,
Massachusetts. I have examined the type and found the spores to