FINK—THE LICHENS OF MINNESOTA. 185 
19a. Lecanora calcarea contorta (Hoffm.) Tuck. Syn. N. A. Lich. 1: 199. 1882. 
Verrucaria contorta Hoffm. Descr. Pl. Crypt. 1: 97. pl. 22. f. 1-4. 1790. 
Thallus better developed, areolate and the areoles frequently more or less scattered, 
commonly pale greenish lead-colored; apothecia scarcely becoming adnate and the 
disk sometimes punctiform; often four spores in each ascus, and the spores of the larger 
size mentioned above. 
The subspecies is well marked. 
Generally distributed over the State. On various rocks, but more common on 
calcareous. 
Elsewhere in North America in Greenland, and various portions of the United States 
from Alabama northward to Illinois and westward to California. Known also in all 
of the grand divisions except Australia. 
20. Lecanora lacustris (With.) Nyl. Not. Sallsk. Faun. Flor. Fenn, 5: 155. 1861. 
Lichen lacustris With. Arr. Brit. Pl. ed. 3. 21. 1796. 
Thallus crustose and usually thin, smooth and only slightly chinky, but becoming 
thicker and plainly areolate, ashy or more commonly varying toward pale brick- 
colored or pale olivaceous, occurring in irregular patches, in the specimens at hand 
15 to 80 mm. across; apothecia small or rather minute, 0.2 to 0.5 mm. in diameter, 
immersed and usually urceolate, in areolate thalli usually several in each areole, the 
disk reddish or brownish; hypothecium pale or slightly cloudy; hymenium pale below 
and commonly somewhat colored above; paraphyses simple or rarely branched, the 
apices sometimes enlarged and slightly colored; asci clavate; spores oblong-ellipsoid, 
11 to 17 » long and 4 to 6 » wide. 
Collected at Tower. On rocks along the shore of Vermillion Lake, in places often 
inundated. 
Elsewhere in North America, in Alaska, Greenland, New England, and Alabama. 
Known in Europe and Asia. 
21. Lecanora subepulotica (Nyl.) Fink. 
Lecidea subepulotica Nyl. Mém. Soc. Sci. Nat. Cherb. 4: 337. 1857. 
Thallus crustose and thickened, verrucose or areolate, whitish-ashy, in ours forming 
small thickened areas from 2 to 6 mm. in diameter, these frequently running together 
to form larger patches; apothecia small, 0.2 to 0.6 mm. in diameter, adnate, the disk 
flat, convex or more or less irregular, flesh-colored to reddish and darkening, the 
exciple soon disappearing, and the whole structure becoming biatoroid, the exciple 
when present and the whole apothecium as well tending to be irregular in form; 
hypothecium pale-brownish to brown; hymenium pale reddish brown; paraphyses 
commonly simple, very slender, sometimes slightly enlarged and brownish toward the 
apex; asci cylindrico-clavate; spores ovoid-ellipsoid, 10 to 16 long and 6 to 9 » wide, 
tending to uniseriate arrangement in the asci. 
Frequently regarded a subspecies of the last, but ours is quite distinct. 
Collected along the northern boundary near Emo. On rocks along Rainy River. 
Elsewhere in North America in Canada, Vermont, Massachusetts, and California. 
Known also in Europe. 
HAEMATOMMA Mass. Ric. Lich. 32. /. 53-54. 1852. 
The thallus is crustose and usually thin. In some of the species there is a more or 
less developed upper cellular cortex, while in others no other cortical structure is 
present than a thin layer of gelatinized and often scarcely distinct hyphe. The algal 
and medullary layers are not often distinctly differentiated, while the lower cortical 
layer seems to be uniformly absent. Hyphal rhizoids form the attaching organs. 
The algal symbionts are rather large, but do not seem to differ otherwise from the 
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