Thallus an ash or green-gray crust, or varying toward brown or brown-black, smooth to more commonly roughened, chinky to areolate, continuous or scattered, of moderate thickness, often widely and irregularly disposed on the substratum; apothecia small to large, 0.5 to 1.3 mm. in diameter, immersed to adnate, black-brown to black, flat with the concolorous exciple visible, or becoming somewhat convex, with the exciple often covered; hypothecium dark brown; hymenium pale, or tinged brown, especially above; paraphyses coherent, semi-distinct; asci clavate or inflated-clavate; spores oblong-ellipsoid, 4-celled to muriform, hyaline to finally brown, 15 to 40 mic. long and 7 to 18 mic. wide. 8 in each ascus (Fig. 9). Collected in Lake, Hocking, and Ross counties. Also examined from Summit, Vinton, and Ashtabula counties. On rocks. Rare but widely distributed in the State. EXPLANATION OF PLATE XIII Fig. 1. Five paraphyses of _Rhizocarpon alboatrum_ to illustrate types of simple and branched forms found in the same hymenium. X 450. Fig. 2. A section of the thallus of _Bacidia rubella_ and two cells of the woody substratum: a, the upper densely interwoven portion of the thallus; b, part of the less densely interwoven portion below; c, the algal-host cells; d, one of the cells of the woody substratum and three hypal rhizoids within it. X 450. Fig. 3. Spores of _Lecidea enteroleuca_ to illustrate the simple, hyaline type. X 760. Fig. 4. Spores of _Biatorina chalybeia_ to illustrate the 2-celled, hyaline type. X 760. Fig. 5. Spores of _Bilimbia trachona_ to illustrate the several-celled, hyaline, fusiform or dactyloid type. X 760. Fig. 6. Spores of _Bacidia fuscorubella_ to illustrate the several-celled, hyaline, acicular type. X 760. Fig. 7. Spores of _Bacidia umbrina_ to illustrate the several-celled, hyaline, hamate or spirally twisted type. X 760. Fig. 8. Spores of _Rhizocarpon alboatrum_ to illustrate the several-celled to many-celled and muriform, hyaline to brown type. X 760. Fig. 9. Spores of _Rhizocarpon petraeum_ of the same type as those shown in the last figure, but larger, and usually composed of more cells. X 760. Fig. 10. A vertical section through an apothecium of _Lecidea rupestris_: a, the hymenium, composed of asci and paraphyses; b, the hypothecium; c, the mycelium, the cells of the algal host, and particles of the limestone on which the plant was growing; d, the weak, light-colored, covered exciple. X 79. Fig. 11. A vertical section through an apothecium of _Buellia parasema_, the thallus below, and a portion of the woody substratum: a, the hymenium, composed of asci and paraphyses; b, the strongly developed, dark colored exciple; c, the dark colored hypothecium; d, the thallus, composed of interwoven hyphae, and enclosing cells of the algal host, a portion of the woody substratum. X 79. Fig. 12. One branched and one unbranched paraphysis of _Buellia parasema_. X 450.