Thallus a thin, smooth or subtartareous, rarely rimose-areolate, ash-white to brown-gray, wide-spread and continuous or finally disappearing crust; apothecia minute to small, 0.2 to 0.5 mm. in diameter, adnate, black, from flat becoming convex and often irregular, the inconspicuous exciple then becoming covered; hypothecium pale to darker brown; hymenium pale or tinged brown; paraphyses distinct to coherent-indistinct; asci clavate; spores oblong-ellipsoid, 8 to 11 mic. long and 2.7 to 4 mic. wide. A single collection was made in Highland County. On exposed calcareous rocks. Not previously reported from Ohio, and doubtless rare in the State. An occasional 4-celled spore was seen, a transitional character previously noted by Th. M. Fries. The plant is closely related to the next below, from which it may not be distinct. 4. Biatorina chalybeia (Borr.) Mudd, Man. Brit. Lich. 180. 1861. _Lecidea chalybeia_ Borr. in Sowerby, Eng. Bot. Suppl. 1: pl. 2687. f. 2. 1831. Thallus a thin, smooth or roughened, ash-gray and darkening crust, forming a continuous layer, becoming inconspicuous and rarely disappearing; apothecia minute to small, 0.3 to 0.5 mm. in diameter, adnate to sessile, concave to slightly convex, black, the exciple concolorous, prominent, and rarely becoming covered; hypothecium dark brown; hymenium pale below and pale brown above; paraphyses wide and strong, distinct to coherent-indistinct; asci clavate; spores oblong-ellipsoid, 8 to 12 mic. long and 3.5 to 4.75 mic. wide (Fig. 4). Collected in Butler County. On calcareous rocks. Not previously reported from Ohio, and probably rare in the State. The spores are somewhat larger than in European specimens. Bilimbia De Not. Giorn. Bot. Ital. 21: 190. 1846. Thallus usually composed of minute granules, these often run together to form a leprose or verrucose and rarely areolate or even subsquamulose crust, rarely disappearing; apothecia minute or small, usually adnate, with a weak and often covered exciple; hypothecium pale to dark brown; hymenium pale or tinged brown; spores hyaline, usually fusiform or dactyloid, varying from 4- to 9-celled. KEY TO THE SPECIES OF BILIMBIA On rocks. Apothecia and spores smaller 5. B. _microcarpa_ Apothecia and spores larger 6. B. _trachona_ On other substrata. On mosses 2. B. _hypnophila_ On wood or bark. Spores becoming more than 4-celled 3. B. _naegelii_ Spores not more than 4-celled. Apothecia flesh-colored to dark brown 1. B. _sphaeroides_ Apothecia black 4. B. _melaena_ 1. Bilimbia sphaeroides (Dicks.) Koerb. Syst. Lich. 213. 1855. Lichen sphaeroides Dicks. Pl. Crypt. Brit. 1: 9. pl. 2. f. 3. 1785.