234 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Thallus darker-colored. 
Thallus ashy-gray to olivaceous or blackish, thick and 
becoming minutely areolate, with apothecia entirely 
immersed.................--- cece cece eee eee eee eee 3. V. fuscella. 
Thallus olivaceous-greenish to dull black, thinner, 
chinky or rarely areolate; the apothecia not so com- 
pletely immersed. 
Thallus brownish black to dull black............-. 4. V. nigrescens. 
Thallus olivaceous-greenish .........22...2...2..-. da. V. nigrescens vi- 
ridula, 
1. Verrucaria epigaea (Pers.) Ach. Meth. Lich. 123. 1803. 
Sphaeria epigaea Pers. Syn. Meth. Fung. App. xxvir. 1801, 
Thallus a thin crust upon the substratum, ashy or greenish in color, often finely 
granulose, widely spread and sometimes disappearing; apothecia very minute, more 
or less immersed, the perithecium dark brown in section, the amphithecium com- 
monly pale; paraphyses often quite distinct; asci cylindrical or cylindrico-clavate; 
spores oblong-ellipsoid, 16 to 28 4 long and 7 to 10” wide. 
Collected in the northern portion of the State at Rainy Lake City, at Harding, 
and about Snowbank Lake. On earth. 
Elsewhere in North America in Massachusetts, Maryland, Virginia, New Jersey, 
Illinois, Iowa, California, Quebec, and Newfoundland. Known also in Europe. 
2. Verrucaria muralis Ach. Meth. Lich. 115. 1803. 
Lichen muralis Ach. Lich. Suec. 60. 1798, 
Thallus usually in part epilithic, smooth and chinky or becoming scurfy or slightly 
granulose, white, whitish, or darkening and widely spread over the substratum as a 
continuous or more or less broken layer, or the epiphleodal portion disappearing; 
apothecia small or minute, but reaching larger sizes than in the last, 0.15 to 0.35 mm, 
in diameter, often becoming largely superficial and appearing as black spots upon 
the substratum, crowned by the minute ostiole, sometimes more or less clustered, the 
perithecium dark brown in section, the amphithecium pale or yellowish; asci cyl- 
indrico-clavate; spores oblong-ellipsoid, 13 to 23 1 long and 6 to 9” wide. 
On calcareous rocks, and found in the State wherever these occur, 
Elsewhere in North America in New England, New York, Vermont, Ohio, Illinois. 
Wisconsin, Iowa, Missouri, Kansas, California, and Canada. Known also in Europe 
and Asia. 
3. Verrucaria fuscella (Turn.) Ach. Lich. Univ. 289. 1810. 
Lichen fuscellus Turn. Trans. Linn. Soc, Lond. 7: 90. pl. 8. f, 2. 1804. 
Thallus forming a rather thick layer over the substratum (often 0.4 to 0.7 mm. in 
thickness), occurring in small rounded or irregular areas or becoming more wide- 
spread, chinky and passing into minutely-areolate conditions, the surface ashy-gray 
varying toward olivaceous or blackish, usually black within, never disappearing; 
apothecia minute, usually completely immersed, frequently more than one in each 
areole, the perithecium dark brown in section, the amphithecium pale or becoming 
colored; asci clavate or cylindrico-clavate; spores ellipsoid, 9 to 14 long and 4 to 7 
wide, 
Generally distributed over the State, but most common in regions where calcareous 
rocks occur. On rocks, usually calcareous, 
Elsewhere in North America in Vermont (?), Alabama, Wisconsin, Hlinois, Iowa, 
California, and Alaska. Known also in Europe and Asia. 
4. Verrucaria nigrescens Pers. Neu. Ann. Bot. Usteri 14: 36. 1795. 
Thallus forming a continuous or more or less broken layer upon the substratum, 
thinner than in the last, chinky and rarely passing into distinctly areolate condi- 
tions, brownish black or dull black, never showing the ashy-gray surface so frequently 
