OF ARTS AND SCIENCES. 235 



thin, at length discrete, entire proper margin ; thalline margin some- 

 what prominent, subentire, or rugose-crenate. Fr. Lichenogr. p. 187. 

 Urceolaria, Ach. 



Limestone, and from this passing to other rocks ; New England. 

 New York, Halsey. 



70. P. scriiposa, Sommerf. Cr. lartareous, rugose-granulate, glau- 

 cous-cinerascent ; hypolh. white ; apoth. immersed, disk urceolate, cse- 

 sious-black, with a connivent, cinerous-blackish proper margin, which 

 is at first covered by the crenate thalline margin. Fr. Lichenogr. p. 

 190. Urceolaria, Ach. — ^. hryophila., Ach. ; cr. rugose ; apoth. 

 smaller, disk emergent, urceolate, with a contracted mouth, thalline 

 margin subevanescent. Fr. I. c. Gyalecta, Ach. 



Rocks, stones, dead wood, trunks, and on the earth ; New England. 

 — /? incrusting mosses; Pennsylvania, Muhl. Arctic America, Rich. 



X. THELOTREMA, Ach. 



Apothecia subconical-truncate, at length open, urceolate-scutelliform ; 

 a discrete, lax, membranaceous, lacerate-dehiscent, interior exciple veil- 

 ing a rigescent disk. Thallus crustaceous. 



T. Iepadi7ium, Ach. Disk blackish, at first csesious-pruinose. Fr. 

 Lichenogr. p. 428. Schcer. ! Sjncil. p. 67. 



Trunks, somewhat rare ; New England. Arctic America, Rich. 

 (Herb. Hook. !). Our Lichen, as well as that of Arctic America, agrees 

 with the European ; and the species is found also in Brazil {Eschwei- 

 ler). 



XL GYALECTA, Ach., Fr. 



Apothecia orbiculate, urceolate, at first closed, then variously dehis- 

 cent, the elevated, discrete, colored border of the exciple surrounding 

 the disk. Disk at first included, like a nucleus, and gelatinous, becom- 

 ing at length open, explanate, indurated. Thallus horizontal, crusta- 

 ceous, somewhat tartareous. 



G. cupularis, Schser. Apothecia radiate-dehiscent, urceolate-open ; 

 border orbicular, elevated, tumid, pale, disk pale-flesh-colored. Fr. 

 Lichenogr. p. 195. 



Rocks (especially limestone and sandstone, Fr.) and on the earth. 

 New York, Halsey. Pennsylvania, Muhl. 



