Thallus of minute, rounded, scattered or sometimes clustered,
straw-colored granules, covering small areas, and usually resting on and
limited wholly or in part by a black hypothallus; apothecia minute to
small, 0.2 to 0.6 mm. in diameter, black, semi-immersed to adnate, at
first flat with a thin somewhat raised exciple, becoming convex with the
exciple finally covered; hypothecium brown; hymenium pale or tinged
brown below and light brown above; paraphyses coherent, distinct or
semi-distinct; asci clavate; spores brown, 4-celled, becoming slightly
constricted at the septa, 15 to 18 mic. long and 5 to 7 mic. wide, 8 in
each ascus.

Collected at Cantwell Cave in Hocking County. On shaded sandstone,
intermingled with an ash-gray, crustose thallus, which appeared like a
sterile _Pertusaria_. The type specimen is deposited in the writer's
herbarium, and a cotype may be seen in the State Herbarium.

The plant resembles _Buellia vernicoma_ Tuck.


2. Rhizocarpon alboatrum (Hoffm.) Th. Fr. Nov. Act. Reg. Soc. Sci. Ups.
III. 3: 337. 1861.

_Lichen alboater_ Hoffm. Lich. Icon. 30. 1784.

Thallus ash-gray varying toward white, commonly spread widely over the
substratum as a continuous or rarely scattered or disappearing, smooth,
chinky, verrucose-areolate, or sometimes mealy crust: apothecia small to
middle-sized, 0.35 to 1 mm. in diameter, adnate or immersed, dull black
and often more or less white-pruinose, flat with the black exciple