OF ARTS AND SCIENCES. 231 



cent; hypothallus pale; apothecia tumid, disk plane, pale, innate-pru- 

 inose, with an erect, entire, persistent nnargin. Fr. Lichenogr. p. 132. 

 Lecanora Parella, /5. Ach. Lichen pallescens, L. Spec. PI. — /?, Parel- 

 Za, Fr. ; crust amylaceous-tartareous, plicate-verrucose, milk-white, disk 

 at length chinky or verrucose. Fr. I. c. Lecanora Parella., Ach. Li- 

 chen Parellus, L. Mant. 



Trunks, rails, stones, &c., ascending to alpine districts. — /5, rocks 

 near the sea and large lakes. New England. New York, Torrey. 

 Pennsylvania, Muhl. Northward to Arctic America, Rich. 



52. P. tartarea, Ach. Cr. tartareous, granulate-conglomerate, glau- 

 cescent; hypoth. pale ; apoth. adnate, disk plane, rugulose, pale-yellow- 

 ish-flesh-colored, with an inflexed, entire margin. Fr. Lichenogr. p. 133. 

 — /5. frigida, Ach. ; hypothallus confused with the thallus ; crust at 

 length granulate, whitish ; apoth. smaller, reddish-flesh-colored. Fr. I. c. 



Rocks ; /? incrusting twigs, mosses, lichens, &c., and ascending to 

 alpine districts ; New England. New York, Halsey. Arctic America, 

 Grev. (PI. W. Greenl.). 



53. P. rubra., Ach. Cr. subcartilagineous, smoothish, at length gran- 

 ulate-pulverulent, glaucescent ; hypoth. pale ; apoth. adnate, disk con- 

 cave, red, with a tumid, inflexed, crenulate margin. Fr. Lichenogr. p. 

 134. Lecanora., Ach. 



Trunks in mountainous districts ; New England. Pennsylvania, 

 Muhl. 



54. P. oculata, Fr. Cr. cartilagineous-tartareous, rugose, uneven, 

 papillose, glaucescent ; hypoth. pale ; apoth. sessile, concave, disk sub- 

 fuscous, with an elevated, very entire margin, which is whiter than the 

 thallus. Fr. Lichenogr. p. 135. — ^5; thallus isidioid, branched ; apoth. 

 becoming black. Fr. I. c. Isidium oculatum, Ach. Turn. Sf Borr. 

 Lich. Brit. p. 103. 



Trunks in mountainous districts ; White Mountains. Northward to 

 Arctic America, Rich., Hook. 



55. P. siihfusca, Fr. Cr. cartilagineous, at first contiguous, smooth, 

 becoming chinky and granulate, glaucescent; hypoth. macular; apoth. 

 adnate, disk plano-convex, subfuscous, whitish within, with an erect 

 margin colored like the thallus. Fr. Lichenogr. p. 136 {excl. P. al- 

 bella). — a. discolor, Fr. ; cr. as above ; apoth. regular, disk thickish, 

 always naked (red, rufous, fuscous, or black), margin entire, or at 



