FINK—THE LICHENS OF MINNESOTA. 175 
ently areolate crust, this sometimes radious at the circumference; or rarely reduced 
to scattered, closely adnate, flattened or hemispherical squamules, greenish straw- 
colored above, beneath commonly black; apothecia. scattered or rarely clustered, 
middle-sized or large, 1.5 to 5 mm. in diameter, sessile or adnate, pale yellow to red- 
dish brown, the thalloid margin thin, flexuous, and sometimes disappearing, the disk 
usually flat, convex or variously irregular; hypothecium pale or pale yellowish, 
hymenium pale below and commonly somewhat colored above; paraphyses simple 
or rarely branched, usually enlarged and colored toward the apex; asci clavate; 
spores ellipsoid, 7 to 15 » long and 4.5 to 8 4 wide. 
Generally distributed over the State. On rocks other than calcareous. 
The plant is generally distributed in North America, but mostly confined to the 
mountains southward. Known also in South America, Europe, and Asia. 
la. Lecanora rubina heteromorpha Ach. Lich. Univ. 412. 1810. 
Thallus somewhat chinky or wrinkled, in ours less inclined to distinctly lobed con- 
ditiors; apothecia of the same color as the thallus or becoming pale brown. 
Probably as widely distributed in the State as the species, though not so common 
and less often observed. Habitat the same as above. 
Elsewhere in North America from Texas, Oregon, and Iowa. Known also in 
Europe. 
2. Lecanora muralis (Schreb. ) Tuck. Gen. Lich. 113. 1872. 
Lichen muralis Schreb. Spic. Fl. Lips. 180. 1771. 
Thallus closely adnate, subfoliose, lobed and the lobes usually somewhat elongated 
and sinuately divided toward the margins, the central portions commonly more or 
less crenate-scaly or areolate, on the whole thinner and more closely attached than 
that of the last, and likewise frequently tending to pass into poorly developed con- 
ditions, the best developed forms usually suborbicular, 10 to 60 mm. in diameter; 
commonly sea-green, the cortical layers composed of closely packed hyphz, or the 
upper perhaps sometimes pseudocellular, the lower very thin; apothecia small to 
middle-sized, 0.65 to 2 mm. in diameter, adnate or rarely somewhat immersed, the 
disk flat or somewhat concave, pale yellowish to tawny brown, the thalloid exciple 
entire, flexuous or crenate; hypothecium pale; hymenium pale below, and _fre- 
quently somewhat brownish above; paraphyses commonly simple, frequently enlarged 
and brownish toward the apex; asci clavate; spores ellipsoid, 9 to 15 » long and 4.5 
to 7» wide. 
Tuckerman’s view has been followed in disposing of the present species and its sub- 
species. Europeans commonly group the subspecies about the next form. 
The plant is generally distributed over the State, usually as one of the subspecies 
below. On rocks. 
Distributed throughout North America in one form or another. Known also in all 
of the grand divisions, most commonly as the first subspecies below. 
2a. Lecanora muralis saxicola (Poll.) Tuck. Syn. N. A. Lich. 1: 184. 1882. 
Lichen saxicola Poll, Hist. Pl. Palat. 3: 225. 1777. 
Form with the thallus lobes much flattened, and normally colored. Our most 
common subspecies. 
Generally distributed over the State. On rocks other than calcareous. 
The most widely distributed North American form, Known also in all of the 
grand divisions. 
2b. Lecanora muralis versicolor (Pers.) Tuck. Syn. N. A. Lich. 1: 185. 1882. 
PLATE 33. 
Lichen versicolor Pers. Ann. Bot. Usteri 7: 24. 1794. 
Thallus smaller and frequently breaking away at one side or in the center, fre- 
quently several thalli closely packed together and even overlapping more or less, 
