North American species of Mycena.

EUMYCENA: ADONIDAE

155

differentiated hyphal tips 28-35 X 6-9,, which may be clavate,
subfusoid, or branched; caulocystidia similar to pilocystidia.
Habit, habitat, and distribution.-Gregarious to subcespitose on
old logs and rich humus; North Carolina, New York, Michigan, and
Missouri in the United States and Ontario and Manitoba in Canada.
It usually occurs in lower Michigan on elm logs or debris, but farther
north I have found it on pine logs.
Material studied.-Smith, 32-281, 32-293, 32-518, 32-521, 33-730,
787, 871, 1368, 1404, 4751, 7146, 7626, 7673, 7690, 11036, 15244.
Bisby, Manitoba. Kanouse, Michigan. Kauffman, four collections
(as M. nivea Quelet), Michigan; one collection (as M. minutula), North
Carolina. Overholts, 1049.
Observations.-The cystidia on the pileus are not always demonstrable on revived material, but have been noted on several of my
collections. The American material differs in some respects from
European specimens, but most of the differences do not impress one as
being constant. I found small pleurocystidia on my four-spored
specimens from Ann Arbor, but observed that on specimens from
farther north the pleurocystidia were rather abundant and within the
size range given by Ktihner (1938). The two-spored specimens from
Ann Arbor had the largest cystidia in the collections, but the difference was only in size. The pilocystidia apparently collapse more
readily than do the caulocystidia, with the result that the pileus often
has a polished appearance when the stipe is still pruinose. The specimens previously referred to M. lactea var. pithya (Smith, 1935b)
belong here. Bisby's report of M. collariata may also be referred to a
form of this variety. Ktihner does not recognize M. collariata.
Varietal ranking has been given to the American material because
it has never been found to have a farinaceous taste pronounced
enough to be distinct. In fact, all my Ann Arbor collections have
been perfectly mild. Bisby (September 18, 1935, St. Vitae Park,
Manitoba) also described it as being without any odor or taste. The
basidia in his collection are nearly all bispored, and the spores measure
7-9 X 6-7,. The cystidia measure 50-80 X 9-12,u.
For a time I regarded this variety as M. lactea Fries because of the
very striking resemblance of the fruiting bodies to the illustration
(Icones Selectae Hymenomycetum) of that species. Kiihner, however,
has followed Lange and used the name "lactea" in a very different
sense. I have abandoned this name for any species because of the
possibilities of confusion. In my estimation Fries's descriptions of