382 Wisconsin Academy of Sciences, Arts, and Letters. 
They represent L. umbilicatus Pk. (N. Y. State Mns. Rept. 28: 51. 
and PI. I, figs. 15-19). The spores are the same as those of 
L. cochleatns. Peck’s description in Bulletin 131, page 45, reads: 
“Pileus fleshy but thin, tough, glabrous, deeply umbilicate, 
hygrophanous, brownish tan color when moist, paler when dry. 
Lamellae close, adnate or decurrent, serrate on the edge, whitish. 
Stem short, slender, glabrous, nearly even, tough, stuffed or hollow, 
central or eccentric, colored like the pileus. Pileus 6-12 lines broad, 
stem 8-12 lines long, 1-1.5 lines thick. Ground and decaying wood, 
gregarious, July and August. This small species resembles Len- 
tinus cochleatus Fr. in texture and color, but it is a much smaller 
plant, gregarious in its mode of growth and without furrows on the 
stem. It is closely related to Lentinus omphalodes Fr. from which 
it has been separated on account of its hollow stem without 
elongated furrows or lacunae and its darker color. ’ ’ 
Note. L. Americanus Pk. (Bull. Torrey Bot. Club 29: 72) differs in the 
more marked reddish brown strigose villosity towards the base of the 
stem and the rather large spores. It was described from plants collected 
in Idaho. It is said to grow most commonly on the ground, but it differs 
from the plants shown in Plate XXVI, C in the very short strigose stem. 
5. Plate XXVI, C. The plants represent an extreme form of the 
small central-stemmed forms of the Lentinus cochleatus group. 
The pileus is nearly regular and even on the margin. The stems 
are long, relatively thick, even, straight, smooth, hollow, whitish 
toward the apex. The plants grew on the ground among moss at 
Neebish, Michigan, in September. They might easily have been 
taken for a form of Clitocyhe obhata, but the tough substance and 
serrate-lacerate gills showed their true relationship. There was 
scarcely any villosity at the base of the stems. 
The Lentinus ursinus-vulpinus Group 
The group consists of large plants with the pilei dimidiate and 
reniform, usually imbricated as in Plate XXVII. The gills are 
lacerate-toothed. The spores are small, subglobose, 3-4 /a in di¬ 
ameter. 
There are two principal forms in our region, L. ursinus and L. vul- 
pinus, the former has the pilei even on the margin and dark fuscous- 
tomentose behind, and the latter has the pilei ridged and reticulate 
on the margin and scrupose behind. They are considered varieties 
by some writers, since intermediate forms occur. 
