188 LECANORA. 



attained by the species. Lich. Univ. p. 395. L. allophana, 



L. rugosa, L. mesophana, & L. Parisicnsis, Nyl. 



b. hypnorum, Schser. ; thallus running over mosses, vari- 

 ously irregular; whitish; apothecia at length middling- sized. 



Spores as in a. L. subfusca, v. epibryon, Sommerf., & Auct* 



L. epibrya, Nyl. 



c. argentata, Ach. ; thallus thinner and smoother ; whitish ; 

 apothecia smaller ; with mostly entire margin. Spores smaller. 

 Lich. Univ. p. 393. Nyl, I, c. Stizenb. I. c. 



d. coilocarpa, Ach. ; thallus thinnish but becoming wrinkled 

 and broken; whitish; apothecia small, sub -entire, black. 



Spores as in c. Lich. Univ. p. 393. Nyl. 1. c. Stizenb. I. c. 



L. coilocarpa, Nyl. 



e. distans, Ach. ; thallus thin, pale ; apothecia small, flat- 

 tish, pale, with a crenulate margin ; often minute. Spores still 



smaller than in the preceding. L. distans, Ach. L. U. p. 397. 



L. distans, v. chlarona, Ach, 1. c. L. subfusca v. chlarona, dein 

 L. chlarona, Nyl. 



Trees, dead wood, rocks, stones, etc., throughout North 

 America, Muhlenberg Catal. 1818 ; b being however confined to 

 alpine districts ; as Mackenzie river; Great Slave Lake ; etc., 



Richardson; and islands of Behring's Straits, Wright. 



Although it doubtless requires some experience to recognize 

 this very common lichen in its various forms, nothing appears 

 to have been gained by the recent attempts to break up the 

 natural group into so-called species. Some twenty of these 

 have been named, but their characterization is far from suffi- 

 cient. In L. subfusca, as here understood, the naked disk is 



without proper margin : but this feature shews itself at length 

 in a minute southern form referable to e (f. diploloma) South 

 Carolina, Eavenel. 



15. L. Hagenij Ach.; thallus thin but passing into verrucu- 

 lose conditions, or, more often, disappearing ; dirty-greenish, or 

 ash-coloured, or whitish ; apothecia small to very small, adnate, 

 thin, flattish ; from pale to reddish-brown, becoming livid, and 

 blackening, naked or gray-pruinose ; the thin margin very com- 

 monly and now persistently crenate ; or at length entire ; often 

 concolorous with the disk ; or now excluded. Spores ellipsoid, 

 7 ~ mic. Lich. Univ. p. 367, excl. v. p ; Syn. p. 167, excl. p. 



