PERTUSARIA. 215 



and difform ; either discrete, or crowded and running together j 

 closed ; depressed often at the centre and thus falsely-lecano- 

 roid j the solitary or few, rarely depressed ostioles either black- 

 ening, colourless, or indistinct. Spores in fours ; sixes ; and 

 eights ; varying no little in size, as from ^ mic. to ^-^ mic. 

 Schcer. Spicil p. 66. Nyl. Scand. p. 181 ; Prodr. N. Gran, 

 p. 36. 



Trees and rocks. Northern and middle States, Muhlenberg 

 Catal. 1818. Canada, Richardson. Ohio, Miss Biddlecome. 

 Illinois, Hall Maryland and Virginia, Tuckerman. North Car- 

 olina, Curtis. South Carolina, Ravenel. Alabama, Beaumont. 

 Florida, Austin. Louisiana, Hale. Texas, Wright. Oregon, 

 Hall. Very various : now not easily distinguishable from the 

 last ; and the depressed and marginate forms resembling now 

 P. Wulfenii, except in colour. 



12. P. pustulata (Ach.) Nyl. ; thallus membranaceous, 

 chinky, now verruculose ; brownish-cream-coloured, now green- 

 ish, pale-yellowish, or white ; apothecia small to very small, 

 hemispherical and difform ; from only slightly prominent becom- 

 ing globular and sub-sessile ; flattened at length above, when 

 the now confluent, scarcely depressed black ostioles become 



disk-like. Spores in twos ; ^'^f mic. Porina, Ach. L. U. p. 



309 ; Syn. p. 110. Pertusaria, Nyl, Prodr. Gall. p. 195. 



Trees, common from New England to Virginia, Tuckerman 

 Gen. 1872. North Carolina, Curtis. South Carolina, Mavenel. 

 Florida, Austin. Alabama, Beaumont. Texas, Wright. Ore- 

 gon, Hall. P. concreta, Nyl. Enum. Gen. p. 117; & Add. in 



Flora, 1876, p. 233 (P. Westringii, Nyl. Obs. Pyren. p. 35), is 

 said to occur, on granitic rocks, in "northern and arctic Amer- 

 ica," as well as in Ireland, and the south of France ; but the 

 lichen is unknown to me, and the published notices of it are not 

 quite clear. In the place first-cited above the plant is placed in 

 the 5-8-sporous section, but in the later diagnoses it is said to 

 belong to the other, or 1-2-sporous section ; as it is said in one 

 place to have an areolate thallus (Obs. Pyren.) and, in another, 

 a continuous, chinky one (Add. in Flora), and the fruit to be 

 convex and wart-like) Obs. Pyren.) or immersed and endocar- 

 poid ( Add. in Flora). Spores in twos ; ^^ mic. ( Add. 1. c.) 



13. P. glomerata (Ach.) Schaer. ; thallus incrusting, cartila- 

 gineous ; glaucescent, and white ; apothecia small to middling- 



