OF ARTS AND SCIENCES. 211 



Trees and rocks, fertile, New England. A small rock-form occurs 

 (N. aspera, Tuckerm. Lich. N. E. I. c), analogous to a similar one 

 of N. resupinatum. 



VI. PELTIGERA, Hoffm. 



Apothecia orbiculate, peltaeform, plane, adnate to the upper side of 

 elongated lobes of the thallus, or more rarely marginal ; with a thin 

 margin of the thallus. Thallus coriaceous-membranaceous, venose on 

 the under side. 



1. P. malacea, Ach. Thallus spongy, soft, smooth, round-lobed, fus- 

 cous-cinerascent, clothed on the under side with a dense blackish to- 

 mentum becoming white towards the margins ; apothecia ascendant, 

 rounded, margin crenulate. Fr. Lichenogr. p. 44. 



Mountainous districts ; on the earth and on shrub firs near the limit 

 of trees, and on rocks at lower elevations, White Mountains. 



2. P. aphthosa, Hoffm. Th. coriaceous, smooth, besprinkled with 

 warts, bright green (and glaucescent) ; reticulated with blackish veins, 

 and fibrillose on the under side ; apoth. large, ascendant, round, with 

 a somewhat lacerate margin. Fr. Lichenogr. p. 44. 



Rocks among mosses, and on the earth. Common in mountain for- 

 ests ; New England. New York, Torrey. Pennsylvania, Muhl. North- 

 ward to Newfoundland, Pylaie; and Arctic America, Rich., R. Br. 



3. P. canina, Hoffm. Th. membranaceous, flaccid, scrobiculate, 

 subtomentose, fuscous-green (and cinerascent, and hoary) ; the under 

 side whitish and reticulated with pale fuscous veins; apoth. ascendant, 

 rounded, at length semi-revolute, vertical. Fr. Lichenogr. p. 45. 



On the earth, rocks, and mossy trunks, common in New England. 

 New York, Torrey. Pennsylvania, Muhl. Northward to Greenland, 

 Gieseke. 



4. P. rufescens, Hoffm. Th. coriaceous, soft, subtomentose, cinere- 

 ous-virescent (and cinereous, and rufescent) ; fuscous-fibrillose on the 

 under side, and reticulated with black-fuscous veins ; lobes rather 

 narrow, with elevated and crisped margins ; apoth. at length vertical, 

 oblong, revolute. Fr. Lichenogr. p. 46. Pellidea spuria, Ach. Tuckerm. 

 Lich. N. E. I. c. 



On the earth, rocks, and trunks among mosses ; New England. 

 Thallus smaller and thicker than in the last. 



