226 PROCEEDINGS OF THE AMERICAN ACADEMY 



lia, 4* a.nf.helina, Acli. — ^. hispida, Fr. ; lacinise ascendant, hispid on 

 the margins, or tubulose-inflated. Fr. I. c. Borrera tenella, Ach. — y. 

 (tribracia), Fr.; lacinise ascendant, squamulose, sparingly fibrillose, 

 pulverulent at the apices. Fr. I. c. Lecanora irihracia, Ach. part. 



Trunks, dead wood, and rocks, very comnnon; New England. New 

 York, Torrey. Pennsylvania, Muhl. Illinois, Russell! Northward 

 to Arctic America, Rich. 



32. P. ccBsia, Ach. Th. subcrustaceous-membranaceous, substellate, 

 gray (and cinerascent), besprinkled with gray sored ia ; pale on the un- 

 der side ; lacinise linear, somewhat convex, subpinnatifid, ciliate-fibril- 

 lose ; apoth. sessile, margin thin, somewhat inflexed, entire, disk at 

 length naked, black. Fr. Lichenogr.p. 83. — «. {stellaia), Fr. ; lacinise 

 stellate-expanded, fibres shorter, soredia regular ; P. ccesia, Ach. ; and 

 the lacinise sometimes very narrow. Fr. I. c. P. dubia, Fl. — /5. {squa- 

 mulosa), Fr. ; lacinise squamulose, short, obsoletely fibrillose. Fr. I. c. 

 Lecanora iribracia, Ach. part. 



Rocks, stones, and dead wood, fertile ; New England. New York, 

 Haisey. Pennsylvania, Muhl. 



33. P. obscura, Fr. Th. submembranaceous, orbicular, not prui- 

 nose, greenish, becoming livid-fuscous when dry ; black and fibrillose 

 on the under side ; lacinise sublinear, somewhat plane, incised-multifid 

 (often sorediiferous, or the margins pulverulent) ; apoth. sessile, very 

 entire, disk naked from the first, black-fuscous. Fr. Lichenogr. p. 84. 

 P. cycloselis, Ach. — ■ ^. ulothrix, Fr. ; lacinise linear, subciliate, apoth. 

 fibrillose below. Fr. I. c. P. ulothrix, Ach. 



Trunks, dead wood, &c., and passing into several degenerate states ; 

 New England. New York (« and /5), HaZsez/. Pennsylvania (/?), ikf«/i/. 

 Ohio (/?), Mr. Lea ! Northward to Arctic America («), Rich. — A very 

 distinct species detected recently by Mr. Oakes (P. Tuckermani, Oakes 

 ms.) may be referred to here. Resembling generally small greenish 

 forms of P. parietina, this differs in the foliose-lobate margins of the 

 apothecia, which are also fibrillose beneath, as in P. obscura, /?. It is 

 common on trunks about Boston {Oakes, Tuckerman), and I have 

 found it on rocks at the White Mountains. It was sent from Ohio by 

 the late T. G. Lea, Esq. (Herb. Russell !), and I have North Carolina 

 specimens from Mr. Curtis. (What is P. fibrosa, Fr., referred to in- 

 cidentally, Lich. pp. 75, 97 .=>) 



