_Lichen simplex_ Dav. Trans. Linn. Soc. Lond. 2: 283 pl. 28. f. 2. 1794. Thallus thin and smooth or thicker and roughened, sometimes subareolate, ash-white to green-gray and darkening, rarely disappearing; apothecia minute to middle-sized, 0.2 to 0.8 mm. in diameter, adnate, scattered or crowded, rounded or variously irregular, black but usually dark red when damp, flat or slightly convex, the thin exciple raised and persistent; hypothecium light or darker brown; hymenium pale or tinged brown; paraphyses semi-distinct to coherent-indistinct; asci cylindrico-clavate; spores oblong-ellipsoid, 3 to 5 mic. long and 1 to 1.5 mic. wide. Collected in Butler, Adams, Montgomery, Hocking, and Ross counties. On limestone. Not previously reported from Ohio, but probably frequent where there is limestone, though inconspicuous and easily overlooked. 2. Biatorella pruinosa (J.E. Smith) Mudd Man. Brit. Lich. 191. 1861. _Lichen pruinosus_ J.E. Smith in Sowerby, Eng. Bot. 32: pl. 2244 1811. Thallus light colored, usually thin and smooth, rarely disappearing; apothecia minute to middle-sized, 0.2 to 1 mm. in diameter, adnate scattered or crowded, flat or slightly convex, the disk pruinose, and the exciple persistent; hypothecium lighter or darker brown; hymenium usually pale; paraphyses coherent and becoming indistinct; asci cylindrico-clavate; spores oblong-ellipsoid, 3 to 5 mic. long and 1 to 1.5 mic. wide. Collected in Butler and Adams counties. On limestone. Not previously reported from Ohio, but often occurring with the last in limestone areas. Lecidea Ach. Meth. Lich. XXX. 32. pl. 2. f. 1, 2. 1803. Thallus smooth, roughened, or verrucose, in some species chinky to areolate, or even subsquamulose, rarely rudimentary and evanescent; apothecia minute to middle-sized, usually adnate, but rarely sessile or immersed, with pale to black, and flat to strongly convex disk; exciple and hypothecium from pale to dark brown in section; hymenium lighter, most commonly pale; spores simple, hyaline, 8 in each ascus. KEY TO THE SPECIES OF LECIDEA