ent; the wall
thick, yellow-brown within and scarcely impressed by the spores; the
outer surface smooth, brown-red to brown or blackish in color, dehiscent
in a circumscissile manner. Capillitium of slender loosely-branched
threads, 1-3 mic. in thickness, the surface merely uneven or very
minutely warted. Spores globose, yellow, 9-10 mic. in diameter. See
Plate I, Fig. 13.

Growing on the inside of the bark of Juglans, Acer, etc. Sporangia
variable in size, 7-1.3 mm. in breadth, irregular and angular, much
flattened. It is said to include _Perichaena vaporaria_, Schw.

2. PERICHAENA IRREGULARIS, B. & C. Sporangia depressed, irregular,
polygonal, crowded, the edges contiguous and sometimes confluent; the
wall thick, yellow inside and faintly reticulately impressed by the
spores, the outer surface smooth, purplish-brown, dehiscent in a
circumscissile manner. Capillitium of slender-loosely branched threads,
about 2 mic. in thickness, the surface minutely warted or spinulose.
Spores subglobose, yellow, 9-10 mic. in diameter.

Growing on the outer bark of Acer, etc. Sporangium .5-.6 mm. in width,
closely crowded and irregular. It is much smaller than _Perichaena
depressa_, and its threads are more distinctly warted and spinulose.

3. PERICHAENA CORTICALIS, Batsch. Sporangia globose, the base depressed,
gregarious: the wall thick, yellow within and distinctly reticulately
impressed by the spores, the outer surface reddish-brown or yellow-brown
in color, dehiscent in a circumscissile manner. Capillitium of slender
loosely-branched threads, about 2 mic. in thickness, the surface very
minutely warted. Spores subglobose, yellow, 10-12 mic. in diameter.

Growing on the inside of the bark of Elm. Sporangia .5-.6 mm. in
diameter, quite regular in shape, with a slightly flattened base. My
specimens are from Prof. McBride, of Iowa.

4. PERICHAENA MARGINATA, Schw. Sporangia depressed, polygonal,
approximate and sometimes confluent, the surface cinereous-pulverulent,
seated on a silvery hypothallus; the wall firm, thick, the outer surface
yellow-brown, covered with minute whitish scales, the inner surface
yellow, deeply reticulately impressed by the spores which rest against
it, dehiscent in a circumscissile manner. Capillitium consisting of a
few simple or somewhat branched threads or well-nigh obsolete. Spores
subglobose, yellow, 12-14 mic. in diameter.

Growing on the outer surface of the bark of Acer, Fagus, etc. Sporangia
.