OF ARTS AND SCIENCES. 229 



41. P. Hypnorum, Fr. Scales of the thallus minute, imbricate, gran- 

 ulate-crenulate, somewhat yellowish-fuscescent ; pale on the under side ; 

 apoth. sessile, dilated, disk membranaceous, fulvous-fuscescent, with 

 an elevated, granulose, thalline margin. Fr. Lichenogr. p. 98. Icon, 

 Laur. in Sturm's Fl. t. 18. 



On the earth, growing over mosses and twigs, in alpine districts. 

 White Mountains, frequent upon Salix Uva-Ursi, on Mount Pleasant, * 

 &c., fertile. Northward to Arctic America, Rich. 



Sect. III. Thallus crustaceous, lobate at the circumference, or wholly 



squamulose and effigurate. 



Subsect. VI. Placodiubi, Fr. 



42. P. straminea, Wahl. Thallus crustaceous, plicate-radiose, straw- 

 colored ; laciniae convex, teretish, contiguous ; apothecia plane, red- 

 dish-fuscous, with a tumid thalline margin. Fr. Lichenogr. p. 109. 



Rocks. Greenland, Fries. And elsewhere in Arctic America, 

 Rich. 



43. P. saxicola, Ach. Th. cartilagineous, appressed, areolate-squam- 

 ulose, pale-greenish ; the circumference of somewhat plane, radiose- 

 lobate, concrete lacinise ; apoth. appressed, disk yellowish-fulvous, mar- 

 gin thin, at length crenate. Fr. Lichenogr. p. 110. Lecanora galacti- 

 na, Ach. 



Rocks and stones, fertile ; New England. New York, Halsey. 



44. P. chrysoleuca, Ach. Th. cartilagineous, subfoliaceous, crenate- 

 lobate, greenish-straw-colored ; fuscescent on the under side ; apoth. ap- 

 pressed, disk golden-fulvous, and dark orange-red, with a thin, flexuous, 

 evanescent margin. Fr. Lichenogr. p. 113. Lecanora ruhina, Ach. 

 Squamaria, Hoffm. Tuckerm. Lich. N. E. I. c. 



Rocks, New England. Northward to Arctic America, Rich. (Herb. 

 Hook.!). 



45. P. oreina, Ach. Th. crustaceous-adnate, areolate-verrucose, 

 pale-greenish-stra\v-colored ; at the circumference radiose-lobate, plane, 

 incised, black-marginate ; apoth. depressed, disk somewhat tumid, black, 

 margin obtuse, very entire. Fr. Lichenogr. p. 113. P. straminea, var. 

 Ach. Mey. Tuckerm. Further Enum. I. c. 



Rocks, throughout New England ; fertile. 



46. P. elegaiis, Ach. Th. stellate-radiose, appressed, dark orange- 



