North American species of Mycena.

PSEUDOMYCENA: BASIPEDES

51

smooth, amyloid; basidia four-spored; pleurocystidia not differentiated; cheilocystidia 18-22 X 7-12 u, ovoid to clavate with
rounded apices which are covered with scattered slender cylindric
prolongations.
Habit, habitat, and distribution.-Gregarious to scattered on oak
leaves, usually late in the fall in company with M. capillaris. I have
records of it only from Michigan, but it apparently is widely distributed.
Material studied.-Smith, 31-668, 32-660, 1169, 1176, 12,68.
Kauffman, October 30, 1929, Michigan.
Observations.-This is a very small delicate species easily distinguished from M. capillaris by the slight basal bulb of the stipe.
I have not studied the trama of the gills and pileus in detail. For a
more complete account of these characters see Kiihner (1938). It is
difficult to make specimens of such a small agaric as this since, by the
time the fruiting bodies have been dried, they are practically invisible.
The gills may appear to be free in small specimens, and in fact sometimes are, but the character has little taxonomic significance. Many
characters which are very constant in larger species are found to be
extremely variable in the minute forms, and one must be very careful
to avoid describing each collection as a new species or variety. Spore
size is a good example. In a single deposit a great range of variation
can be found. Deposits from fresh, unwilted pilei are hard to get,
and the last spores deposited are apt to be rather irregular in size
and shape. Similar differences can be found between collections,
and it is here that one is most likely to be misled. In mounts of revived material the spore size is likely to be smaller than that obtained from spore deposits of perfect specimens. This is apparently
caused by the larger percentage of immature spores that occur in the
mounts of the revived material.
4. Mycena Gaultheri, sp. nov.
Illustrations: Text fig. 1, nos. 8-9 (p. 46).
Pileus 1-3 (4) mm. latus, convexus vel conicus, melleus, striatus;
lamellae adnatae, distantes, latae, pallidae; stipes 2-4 cm. longus,
flexuosus vel strictus, bulbosus, deorsum luteus, sursum pallidus;
sporae 8-9 (10) X 4-5 At; cheilocystidia clavata vel capitata, echinulata. Specimen typicum in Herb. Univ. Mich. conservatum. Legit