256 PROCEEDINGS OF THE AMERICAN ACADEMY 



apothecia appressed, obtusely marginate, glaucous-pruinose, white with- 

 in. JFV. Lichenogr. p. 285. 



On the earth upon mosses ; Arctic America, Rich. 



2. L. vesicularis, Ach. Cr. bullate-plicate, somewhat caulescent, 

 from greenish becoming glaucous, radiculose at the base ; apoth. free, 

 peltate, obtusely marginate, at first pruinose, finally convex, naked ; 

 white within. Fr. Lichenogr. p. 286. 



On the earth in alpine districts ; Arctic America, Rich. 



3. L. Wahlenhergii, Ach. Cr. suborbicular, gyrose-plicate, round- 

 lobed at the circumference, from green becoming bright-yellow ; hy- 

 poth. black ; ' apoth. arising between the areolae, obsoletely marginate, 

 naked, black within.' Fr. ! Lichenogr. p. 291. Icon, Laur. in Sturm's 

 Fl. t. 28. 



Moist sides and crevices of rocks in alpine districts. On the Great 

 Haystack, New Hampshire, infertile. Arctic America, Rich. 



4. h. Jtavo-virescens, Fr. Cr. determinate, areolate-appressed, pli- 

 cate, lobulate at the circumference, from greenish becoming yellow ; 

 apoth. adnate, with a thin margin, becoming at length convex, and ex- 

 cluding the margin, black within. Fr. Lichenogr. p. 291. L. scalrosa, 

 Ach. Meih. 



On the earth in mountainous districts, often in company with Biatora 

 Byssoides ; White Mountains. According to Borrer (in Hook. Br. Fl. 

 2, p. 178), L. citrinella, Ach., is the true Lichen flavo-virescens of 

 Dickson, and the present species should bear the name given it by 

 Acharius. Compare Fries, 1. c. 



Sect. II. Thallus effuse, uniform. 



Subsect. I. Areolat^, Fr. Crust innate, originally areolate or be- 

 coming so. Hypothallus black. 



* S axic ol (B. 



5. L. alho-ccerulescens, Fr. Cr. at first contiguous, from bluish be- 

 coming whitish ; apoth. produced from the crust, margin of the annu- 

 lar exciple thin, disk waxy, black, cerulescent-pruinose, white within. 

 Fr. Lichenogr. p. 295, L. pruinosa, Ach. Tuckerm. Lich. N. E. I. c. 

 — /5. immersa, Fr. ; cr. very thin, whitish, disappearing ; apoth. small, 

 oftener immersed in the rock. Fr. I. c. L. immersa., Ach. 



Rocks and stones, especially granite and mica-slate ; New England. 



