lia, & anthelina, Ach.-B. hispida, Fr. ; laciniæ ascendant, hispid on the margins, or tubulose-inflated. Fr.l.c. Borrera tenella, Ach. (tribracia), Fr.; lacinia ascendant, squamulose, sparingly fibrillose, pulverulent at the apices. Fr. l. c. Lecanora tribracia, Ach. part.

Trunks, dead wood, and rocks, very common; New England. New York, Torrey. Pennsylvania, Muhl. Illinois, Russell ! Northward to Arctic America, Rich.

32. P. casia, Ach. Th. subcrustaceous-membranaceous, substellate, gray (and cinerascent), besprinkled with gray soredia; pale on the under side; laciniae linear, somewhat convex, subpinnatifid, ciliate-fibrillose; apoth. sessile, margin thin, somewhat inflexed, entire, disk at length naked, black. Fr. Lichenogr. p. 83. — a. (stellata), Fr. ; laciniæ stellate-expanded, fibres shorter, soredia regular; P. casia, Ach.; and the lacinia sometimes very narrow. Fr. l. c. P. dubia, Fl. —ß. (squamulosa), Fr.; laciniæ squamulose, short, obsoletely fibrillose. Fr. l. c. Lecanora tribracia, Ach. part.

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

33. P. obscura, Fr. Th. submembranaceous, orbicular, not pruinose, greenish, becoming livid-fuscous when dry; black and fibrillose on the under side ; lacinia 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.-B. ulothrix, Fr. ; lacinia linear, subciliate, apoth. fibrillose below. Fr. l. c. P. ulothrix, Ach.

Trunks, dead wood, &c., and passing into several degenerate states; New England. New York (a and 8), Halsey. Pennsylvania (§), Muhl. Ohio (f), Mr. Lea! Northward to Arctic America (a), 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, 8. 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 incidentally, Lich. pp. 75, 97?)

SECT. II. The subfoliaceous at length subgranulose thallus arising from a fibrillose hypothallus, which is adnate to the matrix.

Subsect. III. PYXINE, Tuckerm.

34. P. sorediata, Tuckerm. Thallus subcrustaceous-foliaceous, laciniate-multifid, from green becoming glaucescent, and cinerascent; black on the under side, and thickly clothed with greenish-nigrescent fibres; laciniæ sublinear, canaliculate, incised, obtuse, irregularly imbricate, and concrete at the centre (often sorediiferous); apothecia at first pale, and concave, becoming black, convex, and finally proliferous-papillate and irregular. Lecidea, Ach. Syn. p. 54. Tuckerm. Further Enum. 1. c. Lichen alomatus, Willd. herb.! Pyxine, Fr. cit. Eschw.

Trunks, common (abundantly fertile in mountain forests), and also on rocks; New England. Pennsylvania, Muhl.! Rocky Mountains, Herb. Hook.! (Southward to Texas!) I have not seen the description of Fries, and am uncertain whether his Pyxine is founded on our Northern Lichen (which is probably what Acharius described), or on the West Indian and South American Lecidea sorediata of Eschweiler. The latter seems distinct, and has been separated as Circinaria Berteriana by Feé (Crypt. Exot. p. 128). Our Lichen appears to me a modification of Parmelia, near to Amphiloma, Fr. The apothecia have some of the features of those of Umbilicaria, and illustrate Fries's observation, that this genus is related to Parmelia.

Subsect. IV. AMPHILOMA, Fr.

35. P. rubiginosa, Ach. Thallus membranaceous, suborbicular, not pruinose, livid-glaucous, laciniate-multifid at the circumference; hypothallus indeterminate, tomentose, bluish-black; apothecia reddishbrown, with an incurved, crenate margin. Fr. Lichenogr. p. 88. — ß. conoplea, Fr.; the centre of the thallus passing into a bluish, pulveraceous-granulose crust; ' apothecia symphycarpeous, immersed, convex, granulose-marginate.' Fr. l. c. P. conoplea, Ach.

Rocks and trunks. has occurred at the White Mountains; and I have a from the South.

36. P. Russellii, Tuckerm. Th. orbicular, coriaceous-membranaceous, minutely farinose-granulose, submonophyllous, irregularly radiant, pale-fuscescent-lead-colored; laciniæ somewhat ascendant; hypoth. indeterminate, of very short white fibres becoming lead-colored at the margins; apoth. (central, very numerous) reddish-chestnut and nigres

cent, with a thick, inflexed, at length rugose, thalline margin. Tuckerm. Enum. Lich. N. Amer. p. 50.

Trunks and dead wood; Hingham, Mr. Russell. Ipswich, Mr. Oakes.

37. P. Cronia, Tuckerm. Th. orbicular, membranaceous, smooth, radiant, submonophyllous, dark-bluish becoming pale-lead-colored; laciniæ plane, with elevated, darker margins (beset with elevated, often blackish points, and isidioid branchlets); hypoth. determinate, dark cærulescent.

Rocks among mosses, common on the coast of Massachusetts, and resembling a Collema; infertile. It is very distinct from P. plumbea.

38. P. lanuginosa, Ach. Th. membranaceous, white, pruinose; in the circumference lobed and crenate; hypoth. tomentose, bluish-black; apoth. rufous-fuscous, with a pulverulent thalline margin. Fr. Lichenogr. p. 88.-B. (granulosa), Fr.; thallus, at the centre, or mostly, granulose-pulverulent. Fr. l. c. (leproso-byssina); the whole thallus dissolved into a leprous-byssine mass. Fr. l. c. Lepraria, Ach.

- *

Rocks in the mountainous districts and on the coast of New England; rarely fertile.

Subsect. V. PSOROMA, Fr.

39. P. microphylla, Stenh. Scales of the thallus cartilagineous, imbricate, crenate, livid-cinereous, compacted at length into a cinereous crust; hypothallus becoming black; apothecia superficial, disk fuscousblack, finally convex, and excluding the thalline margin. Fr. Lichenogr. p. 90. Lecidea, Ach.

Rocks in woods, fertile; New England.

40. P. triptophylla, Fr. Scales of the thallus membranaceous, lividfuscescent, at first stellate-expanded, and lacerate-dissected, at length granulose-coralline; hypoth. bluish-black; apoth. somewhat immersed, disk rather plane, rufous-fuscous, margin erect, persistent. Fr. Lichenogr. p. 91. a. coronata, Fr. ; apoth. produced from the thallus, with a thalline margin, and either simple or symphycarpeous. Fr. l. c. Lecanora brunnea, Ach. part.-B. Schraderi, Schær.; apoth. produced from the hypothallus, plane, destitute of a thalline margin. Fr. 1. c. y. corallinoides, Fr. ; crust blackish from the predominant hypothallus, squamules wholly coralline. Fr. l. c.

Rocks in woods; New England. New York, Halsey. Pennsylvania, Dill. Northward to Arctic America, Rich.

41. P. Hypnorum, Fr. Scales of the 'thallus minute, imbricate, granulate-crenulate, somewhat yellowish-fuscescent; pale on the under side; apoth. sessile, dilated, disk membranaceous, fulvous-fuscescent, with an elevated, granulose, thalline margin. Fr. Lichenogr. p. 98. ICON, Laur. in Sturm's Fl. t. 18.

On the earth, growing over mosses and twigs, in alpine districts. White Mountains, frequent upon Salix Uva-Ursi, on Mount Pleasant, &c., fertile. Northward to Arctic America, Rich.

SECT. III. Thallus crustaceous, lobate at the circumference, or wholly squamulose and effigurate.

Subsect. VI. PLACODIUM, Fr.

42. P. straminea, Wahl. Thallus crustaceous, plicate-radiose, strawcolored; laciniæ convex, teretish, contiguous; apothecia plane, reddish-fuscous, with a tumid thalline margin. Fr. Lichenogr. p. 109. Rocks. Greenland, Fries. And elsewhere in Arctic America, Rich.

43. P. saxicola, Ach. Th. cartilagineous, appressed, areolate-squamulose, pale-greenish; the circumference of somewhat plane, radioselobate, concrete laciniæ; apoth. appressed, disk yellowish-fulvous, margin thin, at length crenate. Fr. Lichenogr. p. 110. Lecanora galactina, Ach.

Rocks and stones, fertile; New England. New York, Halsey.

44. P. chrysoleuca, Ach. Th. cartilagineous, subfoliaceous, crenatelobate, greenish-straw-colored; fuscescent on the under side; apoth. appressed, disk golden-fulvous, and dark orange-red, with a thin, flexuous, evanescent margin. Fr. Lichenogr. p. 113. Lecanora rubina, Ach. Squamaria, Hoffm. Tuckerm. Lich. N. E. 1. c.

Rocks, New England. Northward to Arctic America, Rich. (Herb. Hook.!).

45. P. oreina, Ach. Th. crustaceous-adnate, areolate-verrucose, pale-greenish-straw-colored; at the circumference radiose-lobate, plane, incised, black-marginate; apoth. depressed, disk somewhat tumid, black, margin obtuse, very entire. Fr. Lichenogr. p. 113. P. straminea, var. Ach. Mey. Tuckerm. Further Enum. 1. c.

Rocks, throughout New England; fertile.

46. P. elegans, Ach. Th. stellate-radiose, appressed, dark orange

red, naked on both sides; laciniæ somewhat discrete, linear, convex, contiguous, flexuous; apoth. of the same color, very entire. Fr. Lichenogr. p. 114.

Rocks and stones near the sea, fertile; New England. Northward to Newfoundland, Pylaie, Point Lake, &c., Rich., and Melville Island, R. Br.

47. P. murorum, Ach. Th. crustaceous, adnate, contiguous, in the circumference radiose-plicate, pale yellow; white underneath; apoth. sessile, disk naked, dark yellow, with a thin, entire, somewhat flexuous margin. Fr. Lichenogr. p. 115.-8. miniata, Fr.; th. verrucose, less and more narrowly radiose, naked, vermilion-colored. Fr. l. c. Lecanora, Ach.

Rocks and stones near the sea, New England, fertile. sylvania, Muhl. Arctic America, Rich.

Subsect VII. PSORA, Fr.

ß, Penn

48. P. molybdina, Wahl. Thallus crustaceous, areolate-verrucose, radiate-plicate, dark-fuscous; white beneath; lacinia of the circumference linear; apothecia innate, disk urceolate, blackish-fuscous, marginate, with a tumid thalline margin. Fr. Lichenogr. p. 126.

Rocks. Greenland, Fries.

49. P. cervina, Sommerf. Th. areolate-squamaceous; the scales crustaceous, subpeltate, repand or lobed, from greenish becoming lividchestnut; on the under side white; apoth. at first immersed, marginate, at length protuberant, disk rufous-fuscous. Fr. Lichenogr. p. 127. -B. squamulosa, Fr. ; th. chestnut-tawny; apoth. naked, thalline margin thin or wanting. Fr. 1. c.

Rocks. White Mountains. Northward to Arctic America, Rich.

50. P. chrysomelana, Ach. (sub Lecanora). Th. crustaceous, areolate, yellow; areola flat, submembranaceous, somewhat lobate, here and there discrete; apoth. appressed, disk plane, sanguineous-black, thalline margin elevated, subrugose, at length flexuous. Ach. Syn. p. 148.

North America (Pennsylvania?), Muhl., Ach.

SECT. IV. Thallus crustaceous, uniform.

Subsect. VIII. PATELLARIA, Fr.

51. P. pallescens, Fr. Crust subtartareous, rugose-granulate, glauces