OF ARTS AND SCIENCES. 275 



as well as Sprengel, refers E. glaucum, Ach, (North America, Ach.), 

 to the variety a of the present species. I have not found this variety, 

 but the next species is near to it. 



2. E. Muhlenbergii, Ach. Th. cartilagineous-coriaceous, thick, 

 from greenish-glaucous becoming fuscescent, very finely rugose and 

 somewhat chinky ; on the under side fuscous-black ; ostioles convex. 

 Ach. Syn. p. 101. 



Rocks. North America, Ach. West Point, New York, Russell ! 

 (Cf. Ach. Syn. pp. 101, 103.) 



3. E. Jluviatile, DC. Th. cartilagineous-membranaceous, flaccid, 

 lobed, green, becoming fuscescent when dry; lobes rounded, somewhat 

 auriculate-lobulate, on the under side naked, reticulate-rugulose, pale- 

 fuscous, becoming black; ostioles somewhat prominent, black. Fr.! 

 Lichenogr. p, 409. E. miniatum, y. aquaticum, Schcer. ! Spicil. p. 60. 

 E. Weberi, Ach. — /S. fulvo-fuscum, Tuckerm. ; th. thick, subcoria- 

 ceous, submonophyllous, with auriculate-lobulate, somewhat inflexed 

 margins, fuscous-fulvescent ; on the under side reticulate-rugose, dark- 

 fulvous-fuscous becoming black ; ostioles scarcely prominent, dark-red- 

 dish nigrescent. 



Rocks (granite), suffused with water; New England. New York, 

 Halsey. Newfoundland, Pylaie. — /5, alpine. Lake of the Clouds, 

 White Mountains, at an elevation of five thousand feet. Fries re- 

 marks, in comparing the present species with E. miniatum, a, that 

 monophyllous specimens of the former are always minute ; but in /3 

 these occur nearly as large as average specimens of the latter. The 

 very brief indication given by Persoon (Act. Wetterav.) of his E. 

 Americanum answers to our variety. 



4. E. pusillum, Hedw. Th. cartilagineous, squamulose-foliaceous, 

 smooth, brownish-olivaceous, pale on the under side, arising from a 

 black, fibrillose hypothallus ; ostioles black, somewhat prominent, per- 

 tuse. Fr. Lichenogr. p. 411. E. Hedicigii, Ach., ^ E. lachneum (f- 

 squamulosum, Ach. {e Fr.). 



On the earth, and rocks, especially of the more recent formations. 

 Pennsylvania, Muhl. New York, Halsey. Apparently wanting in the 

 granite region of New England. 



5. E. IcBtevirens, Turn. Th. thin, membranaceous, irregularly orbic- 

 ular, somewhat concave, round-lobed, grass-green, margins very entire. 



