exciple visible, or convex with the exciple covered;
hypothecium pale or darker brown; hymenium pale; paraphyses stout,
distinct, but often loosely coherent; asci clavate or inflated-clavate;
spores brown, 2-celled, oblong to oblong-ellipsoid, 8 to 13 mic. long,
and 4 to 6 mic. wide, 8 in each ascus.

Collected in Lake County. On exposed igneous rocks. The type specimen is
deposited in the writer's herbarium, and a cotype may be found in the
State Herbarium.

This species is a coarser plant than _Buellia turgescens_ (Nyl.) Tuck.,
with much stronger, darker thallus and apothecia on the whole larger.

Rhizocarpon Ram. in Lam. & DC. Fl. Fr. ed. 3. 2: 365. 1805.

Thallus usually verrucose, areolate or subareolate, tending toward
squamulose conditions, better developed than in other members of the
family, scarcely ever showing granulate conditions, and never
disappearing entirely; apothecia also larger than in the other genera,
adnate to immersed, usually black, but rarely white-pruinose;
hypothecium usually dark brown; hymenium pale to light brown; spores
4-celled to muriform, and pale to brown, various conditions of septation
and coloration sometimes appearing in the same hymenium.

KEY TO THE SPECIES OF RHIZOCARPON

On bark 2. R. _alboatrum_
On rocks.
Spores smaller and 4-celled 1. R. _vernicomoideum_
Spores larger and becoming muriform 3. R. _petraeum_

1. Rhizocarpon vernicomoideum sp. nov.

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. Rhizo