FINK—THE LICHENS OF MINNESOTA. 177 
in suborbicular patches, 2 to 6.5 cm. in diameter or more commonly irregularly and 
more widely spread over the substratum, sea-green varying toward whitish ash-color, 
scarcely corticate; apothecia small to middle-sized, 0.9 to 2 mm. in diameter, adnate 
or more or less immersed, the disk very black, flat or somewhat convex, the exciple 
entire or rarely flexuous or crenulate, very rarely disappearing, and occasionally 
blackening; hypothecium and hymenium brown or blackish brown, or appearing 
black under a hand lens; paraphyses somewhat coherent, but apparently simple, 
usually somewhat colored throughout, and darker and thicker toward the apex; asci 
clavate; spores ellipsoid, 10 to 15 » long and 5 to 7 » wide. 
The plant is difficult to distinguish from the next species and from Lecanora sub- 
usca coilocarpa, but the dark hymenium and hypothecium serve to differentiate it. 
Collected at Taylors Falls. On the igneous rocks, 
Generally distributed throughout North America. Known also in all of the grand 
divisions. 
5. Lecanora frustulosa (Dicks.) Ach. Lich. Uniy. 405, 1810. 
Lichen frustulosus Dicks. Pl. Crypt. Brit. 8:13. pl. 8. f. 1. 1793. 
Thallus crustose and rather thick, the central portions areolate or verrucose-areolate, 
the areoles or verruce much raised and irregular (globose-frustulose ) or even subsquam- 
ose, the margin usually more plainly squamulose and subfoliose, commonly suborbicu- 
lar, covering considerable areas of the substratum, usually 2.5 to 10 cm. in diameter, 
the areoles somewhat scattered, or more commonly crowded and subimbricate; sea- 
green varying toward ashy or yellowish, sometimes showing a cellular cortex, and 
the algal and medullary layers frequently quite distinct; apothecia small to middle- 
sized, 1 to 2 mm. in diameter, sessile, the disk flat or somewhat convex, reddish 
brown to black, the exciple persistent or rarely disappearing, entire or subcrenate; 
hypothecium pale; hymenium pale below and brownish above; paraphyses simple 
or rarely branched, commonly enlarged and brownish toward the apex; asci clavate; 
spores ellipsoid, 9 to 15 » long and 5 to 7.5 » wide. 
Distributed throughout the northern portion of the State and also found on the 
granitic rock exposures of the Minnesota River valley, there collected at Redwood 
Falls and at Granite Falls. On rocks other than calcareous. 
Elsewhere in North America in Greenland, New England, South Dakota, Colorado, 
and California. Known alsoin Europe and Asia. 
6. Lecanora sordida (Pers.) Th. Fr. Nov. Act. Soc. Sci. Ups. IIL. 8: 215. 1861. 
Lichen sordidus Pers. Ann. Bot. Usteri 7: 26. 1794. 
Thallus crustose, rarely unbroken, but more commonly chinky or areolate, rather 
smooth or the areoles somewhat raised and irregular, usually widely and irregularly 
spread over the substratum, the margins sometimes obscurely subsquamulose, scarcely 
corticate, commonly whitish varying toward gray or rarely brownish; apothecia 
usually small, 0.75 to 1.5 mm. in diameter, adnate or more or less immersed, the disk 
flat or convex, flesh-colored to black but whitish-pruinose, the exciple entire and 
rarely disappearing; hypothecium pale; hymenium pale beneath and commonly more 
or less brownish above; paraphyses simple or rarely branched, commonly enlarged 
and brownish toward the apex; asci clavate; spores ellipsoid, 7 to 14» long and 5 to 7 x 
wide. 
Collected in the northeastern portion of the State at Grand Portage, at South Fowl 
Lake, and in the Misquah Hills. On high bluffs. 
Distribution in North America essentially the same as that of the last species above, 
but the present species has been met in New York and at several places in British 
America. Known also in all of the grand divisions except Australia, 
