[Vor. 1 
108 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
often radially elongate, averaging 2 to a mm. in transverse 
direction and about 1 to a mm. in axial direction; stipe central 
or subcentral, concolorous with the pileus, fuscous-squamulose 
to glabrous above, often hispid at the base, 2-6 em. long, 2-4 
mm. thick; spores white, smooth, elliptical-cylindrical, usually 
2-3 guttulate, 2-3 x 6-8.5 y. 
On dead wood. Common. 
This species is much more common than the preceding and 
is distinguished from it by the lighter colored pileus, the ciliate 
margin, the hispid stipe base, and the larger and more alveolar 
tubes. Is is usually found in the spring and early summer. A 
small form of it with the pileus not more than 1 em. in diameter 
is especially common on twigs and bits of wood during the late 
spring and early summer. Murrill regards this form as a dis- 
tinct species and has named it P. arculariformis (Torreya 4: 
151). It is here maintained as a form of P. arcularius. This spe- 
cies is well represented by Hard (Mushrooms f. 336). 
32. P. pennsylvanicus Sumstine, Jour. Myc. 13: 137. 1907. 
Pileus stipitate, circular in outline, depressed, sometimes 
umbilicate or somewhat infundibuliform, 4-6.5 cm. in diameter, 
0.2-0.5 em. thick, fleshy-tough, pale tan or ochraceous buff in 
color, with a thin cuticle, glabrous, azonate, margin thin and 
acute; context white, soft and watery when fresh, with a sweet 
acid odor, rather fragile when dry, 2-4 mm. thick; tubes white 
at first, discolored on drying, long decurrent on the stipe, 2-4 
mm. long, mouths angular, thin walled, large, somewhat longer 
in the radial direction, 1-2 mm. long, 0.5 to 1 mm. wide; stipe 
central or excentric, whitish, glabrous, expanding above, 2-3 
cm. long, 0.4-1 cm. thick; spores white, smooth, oblong-ellip- 
tical or fusoid, 4.2-5.7 x 10-14 и, often once to several times 
guttulate. 
Growing on old logs in July and August. Frequent. 
The above description is drawn from notes and specimens 
from two collections made at Oxford, Ohio, one in August, 
1910, and the other in July, 1911. The odor of the fresh plant 
is described by the author as “nitrous”. Тһе large angular 
pores ally the species with P. arcularius Batsch. ex Fries and 
with Favolus canadensis Klotzsch. From the former it is eas- 
Пу separated by the much larger spores and from the latter by 
