8. E. prunastri, Ach. Th. subfoliaceous, ochroleucous (and pallescent), lacinia linear-attenuate, rugose-lacunose; on the under side somewhat channelled and white; apoth. subpedicellate, cyathiform, rufous. Fr. Lichenogr. p. 25.

Trees and shrubs, more rarely on stones and rails. Arctic America, Rich. Canada, fertile, Herb. Hook.! More common with us in degenerate states. New England. New York, Torr. Pennsylvania, Muhl.

9. E. furfuracea, Mann. Th. subfoliaceous, glaucous (oftener cinereous-furfuraceous), lacinia linear, dichotomous; channelled and becoming black on the under side; apoth. pedicellate, disk rufescent. Fr. Lichenogr. p. 26. Borrera, Ach. ß. Cladonia, Tuckerm.; suffruticulose, naked, lacinia patent, much branched, and often somewhat thyrsoid-entangled.

Trunks, common and fertile; more rarely on stones, &c.; New England. New York, Halsey. P, firs and other trees, on the mountains of Northern New England, fertile.

III. RAMALINA, Ach.

Apothecia rounded, scutelliform, thick, pedicellate-subpeltate, scattered upon both sides of the thallus, disk open, placed upon the (green) gonimous stratum. Thallus originally erect, ramose-laciniate, similar throughout, and of the same color.

Two species occurring in the North of Europe are as yet wholly wanting with us: R. pollinaria, Ach., with a softish, flaccid, corrugated thallus besprinkled with white powdery spots; and R. scopulorum, Ach., with a thick, rigid, polished, often terete thallus, attaining to a very large size. At the extreme South, we may possibly have some West Indian species, or others peculiar to this continent. The late Mr. Menzies kindly presented me with two, collected by him on the coast of the Mexican State of California, which may be noticed briefly in this place. It is probable the first, at least, has been already described, but I have not been able to find any account of it. R. retiformis, Menz. herb. ;' subcartilagineous, much elongated, the irregular flexuous branches dilated above and regularly reticulate-perforate; apoth. lateral. Monterey!- R. Menziesii, Tuckerm.; submembranaceous, thin, deeply lacunose or plane, canaliculate, smooth; apoth. lateral, sessile, with a thin, elevated margin. R. scopulorum? Menz. herb. R. scopulorum, var. tenuissima, Hook. & Arn. in Beechey's Voy.

p. 163? Monterey! Appears to me to differ from R. scopulorum in its softish, plane, often deeply lacunose, and thin thallus, as well as in the apothecia. RoCCELLA, a genus nearly allied to the present and the last, and diffused throughout the warmer regions of the globe, has not as yet any North American representative. I saw, however, in a small collection of "Algæ from Carolina, Bermudas, and the Caribbees, by the Rev. Mr. Clerk," in the British Museum, a Roccella, which resembled R. phycopsis, Ach.; but it is uncertain at which of the above localities this Lichen was obtained.

1. R. calicaris, Fr. Thallus ramose-foliaceous, cartilagineous, rigescent, lacunose, glaucous; apothecia pedicellate, with elevated margins, disk plane, palish. Fr. Lichenogr. p. 30.a. fraxinea, Fr. ; lacinia longer and broader, the fertile ones plane; apoth. lateral. R. fraxinea, Ach. -ß. fastigiata, Fr.; laciniæ shorter, fastigiate, subcompressed, lacunose; apoth. somewhat terminal. R. fastigiata, Ach. ―y. canaliculata, Fr.; laciniæ sublinear, narrow-attenuate, fertile ones channelled; apoth. affixed to the reflexed apices. Lichen calicaris, L. R. fastigiata, B., Ach.-8. farinacea, Schær. ; laciniæ linearattenuate, sublacunose (sorediiferous), rigid; apoth. scattered. R. farinacea, Ach.

ß.,

Very common: a, ß, and y, on trees, rails, &c.; the last especially in mountain forests; d, abundant in the New England mountains, and northward, on trees and rocks. New York, Torrey. Pennsylvania, Muhl.

2. R. polymorpha, Ach. Th. cæspitose, cartilagineous-rigid, longitudinally costate-rugose, glaucous (and pallescent), often sorediiferous and the soredia capituliform; apoth. subterminal, pedicellate, with elevated margins, disk concave, pale. Fr. Lichenogr. p. 32.- ß. tinctoria, Ach.; laciniæ sublinear, diffuse, linear-lacunose, lacerate-incised and pulverulent at the apices. Ach. Lichenogr. p. 601.

Rocks and stones, fertile; New England, and westward, very common. New York, Halsey. Pennsylvania, Muhl. Arctic America, Rich.

IV. CETRARIA, Ach., Fr.

Apothecia scutellate-peltate, affixed obliquely to the apices of the thallus. Thallus cartilagineous-membranaceous, originally ascendant; smoothish on the under side; lobes either somewhat terete, or foliaceous and somewhat concave above.

All the European species, and indeed all that belong to the genus (as revised by Fries) in the last general work of Acharius (Synopsis), occur with us, with several others. It is difficult to define strictly the limits between the foliaceous species of Cetraria and some Parmelia of the subsection Imbricaria; and in his Flora Scanica, Fries has suggested the possibility of extending Cetraria to include most or all of the Imbricariæ. But the genus, as limited in the Lichenographia Europæa, seems a natural one, and well distinguished from Parmelia.

1. Cartilaginea, Fr. Thallus cartilagineous, suberect. 1. C. tristis, Fr. Thallus fruticulose, horny-cartilagineous, rigid, solid, distichally dichotomous, pitch-black, branches fastigiate, terete; apothecia terminal, plano-convex, disk fuscous-black. Fr. Lichenogr. p. 34. Cornicularia, Ach.

Alpine and arctic rocks. Arctic America, Rich.

2. C. odontella, Ach. Th. fruticulose, rigid, solid, subcompressed, palmate-ramose, dark-brownish-chestnut, branches plane, dentate (not ciliate-spinulose); apoth. terminal, plane, disk fuscous. Fr. Lichenogr. p. 35.

Stones and moist rocks in alpine districts. Newfoundland, Despreaux in herb. Deless.! Bory in herb. Kunth! fertile. Northward to Arctic America, Herb. Hook.! Melville Island, R. Br. (Parry's First Voy.).

3. C. aculeata, Fr. Th. fruticulose, rigid, subfistulous, lacunosecompressed, very much and irregularly branched, dark-brownish-chestnut, branches divaricate, black-spinulose; apoth. terminal, peltate, denticulate, disk of the same color. Fr. Lichenogr. p. 35. Cornicularia, Ach.

On the earth in alpine and subalpine districts. White Mountains, fertile. Northward to Arctic America, R. Br., Hook.!

4. C. Richardsonii, Hook. Th. subfoliaceous, canaliculate, divaricate-bipinnatifid, naked or sparingly black-denticulate, dark-chestnut; apoth. marginal, subpedicellate, margin granulate or irregular, disk yellowish-brown. Hook. in Frankl. Narr. p. 761, & Icon, t. 31.

Barren grounds north of Great Slave Lake, Rich. (herb. Hook.! & herb. Grev.!). Prostrate.

5. C. Islandica, Ach. Th. subfoliaceous, sublinear, canaliculate, ciliate-spinulose, olivaceous-chestnut; apoth. obliquely scutellate, adnate to the upper side of the lobes, very entire, disk dark-chestnut.

Fr. Lichenogr. p. 36. — ß. platyna, Fr. ; laciniæ broader, flattish, waved. Fr. 1. c.—y. crispa, Ach.; lacinia narrow, crisped, with connivent margins. Fr. l. c.

On the earth in alpine and subalpine districts, and at lower elevations northward, abundant and fertile; y not found elsewhere. Also degenerate and sterile on hill-sides, and in sandy fields near the coast, throughout New England. New York, Torrey. Pennsylvania, Muhl.

6. C. cucullata, Ach. Th. subfoliaceous, sinuate-laciniate, ochroleucous, sanguineous-fuscous at the base, margins connivent and waved; apoth. adnate to the under side of the lobes, disk pale-flesh-colored. Fr. Lichenogr. p. 37.

On the earth in alpine and subalpine districts. White Mountains, fertile. Northward to Arctic America, Rich.

7. C. nivalis, Ach. Th. foliaceous, erectish, lacunose-reticulate, lacerate-laciniate, ochroleucous, yellowish at the base; laciniæ canaliculate-patulous, crisped; apoth. marginal, crenulate, yellowish-flesh-colored. Fr. Lichenogr. p. 38.

On the earth in alpine and subalpine districts. White Mountains, fertile. Northward to Arctic America, R. Br. (Scoresby).

II. Membranacea, Fr. Thallus coriaceous-membranaceous, the sterile fronds subdepressed.

8. C. glauca, Ach. Th. membranaceous, foliaceous, expanded, sinuate-lobed, ascendant, glaucous (and cinerascent); becoming black on the under side; apoth. terminal, peltate, dark-reddish-chestnut. Fr. Lichenogr. p. 38.a. fertilis, Fr. ; lacinia elongated, channelled, becoming whitish on both sides, or spotted with white. Fr. l. c. p. sterilis, Fr.; laciniæ shorter, wider, subdepressed, the under side fuscous-black. Fr. l. c.

Trunks of trees, stones, &c., in mountain forests, and elsewhere; New England. Northward to Newfoundland, Pylaie.

9. C. sepincola, Ach. Th. membranaceous, foliaceous, ascendant, laciniate, from green becoming olivaceous-fuscescent; paler beneath; lacinia plane (the margins sometimes crisped, pulverulent), fertile ones short; apoth. adnate to the upper side of the lobes, dark-fuscous. Fr. Lichenogr. p. 39.

Trees and dead wood. White Mountains, fertile.

Branches of dwarf firs,
Arctic America, Rich.

with C. pinastri, Hudson's Bay,

Herb. Banks! Northwest Coast, Menzies!

10. C. ciliaris, Ach. Th. subcoriaceous, foliaceous, reticulate-lacunose, greenish glaucous becoming fuscescent; whitish-fuscescent beneath; laciniæ ascendant, crisped, ciliate or black-denticulate; apoth. elevated, blackish-fuscous, with a crenate margin. Ach. Syn. p. 227.

Trunks of trees, and old rails, common and fertile; ascending to subalpine districts, where it is often very small, and resembles the last; New England. New York, Halsey. Pennsylvania, Muhl.!

11. C. lacunosa, Ach. Th. cartilagineous-coriaceous, foliaceous, round-lobed, rugose-reticulate-cellulose, glaucescent; whitish on the under side, or spotted with white; laciniæ ascending, the margins crenate, crisped, black-denticulate; apoth. large, elevated, dark-reddish, entire. Ach. Meth. 295, t. 5, f. 3, Syn. p. 227. Lichen cavernosus, Menz. herb.ß. Atlantica, Tuckerm.; cartilagineous-membranaceous, lacunose-reticulate; apoth. at length perforate. C. lacunosa, Hals. Lich. N. Y., l. c. & Auct. Amer. C. Tuckermanii, Oakes in Sill. Jour.

Trunks of trees, and old rails. a, Northwest coast, Menzies! P, Lake Superior to New England, fertile. New York, Halsey. Pennsylvania, Muhl. The plant of Menzies differs from ours considerably, but more specimens of the Oregon Lichen are required, to settle the distinctness of the two.

12. C. placorodia, Tuckerm. Th. subcartilagineous, foliaceous, of narrow, at first smooth and discrete, at length convex, concrete, and plicate lobes, finally besprinkled with black grains or wholly isidiophorous, pale livid-glaucous; on the under side fuscescent, rugose, smooth, sparingly fibrillose; laciniæ crisped, crenate; apoth. marginal, peltate on the ascending lobules, from pale fuscous becoming dark chestnut, with an inflexed crenate margin, at length explanate. Parmelia placorodia, Ach.! Syn. p. 196.

Trunks (normal), Chelmsford, Russell! and common on rails, when (like C. ciliaris, C. lacunosa, and others) it assumes a Parmeliaceous aspect. From Parmelia it appears to me distinct, in its marginal, obliquely affixed apothecia, and its smooth, reticulate-rugose under-side. Acharius was acquainted only with the rail-Lichen.

13. C. aurescens, Tuckerm. Th. subcoriaceous, foliaceous, plane, sinuate-lobed, yellowish-green; beneath whitish with pale fuscescent fibres; margins of the lobes elevated, crisped, black-denticulate; apoth. large, elevated, chestnut, with a thin crenulate margin.

Trunks and branches of Coniferæ, New Hampshire. And old rails, Massachusetts.