220 LICHENES. [Cctraria. 



B. Upper and wider-surfaces of the thallus nearly alike. 



a. Thallus usually compressed and laciniated. Apothecia scutelli- 

 form (scutellm). 



26. Cetraria. Ach. Cetraria. 



Thallus foliaceous, cartilagineo-membranaceous, ascending- and 

 spreading, lobed and laciniated, on each side smooth and naked. 

 Apothecia orbicular, obliquely adnate with the margin of the 

 thallus, the lower portion being free, (not united with the 

 thallus); the disk coloured, plano-concave, with a border formed 

 of the thallus and inflexed. — Named from cetra, an ancient 

 buckler made of hide, which the apothecia are supposed to resem- 

 ble. — The species are eminently northern or alpine plants. 



1. C. juniperina, Ach. (golden Cetraria); thallus pale yellow 

 deeper beneath, the segments plane ascending erose crenate and 

 crisped, apothecia elevated bright-bay the border crenulated. — 

 Ach. Sy?i. p. 226. — Lichen juniperinus, Linn. — (3. pinastri ; 

 thallus with the segments depressed bluntly lobed crenate the 

 margins crisped pulverulent very yellow. Ach. Syn. 1. c. — 

 Lichen pinastri, Scop. — Dicks — E. Bot. t. 2111 — L. juniper- 

 inus, Lightf. 



On trunks of trees. /3. in the north of Scotland, principally on 

 the Scotch Fir. Frequent about Aviemore, and at Kinnordy, the Seat 

 of Chas. Lye/l, Esq. Park pales at Framingham, near Norwich, Mr. 

 Turner. — The. fructification, though I have gathered it not unfrequently 

 in Switzerland, has, I believe, never been found in Britain. 



2. C. sepincola, Ach. (Fence Cetraria); thallus olive-brown 

 paler and pitted beneath the segments flattish ascending lobed 

 waved subcrenate powdery, apothecia nearly marginal elevated 

 chestnut-coloured with a crenate and wrinkled border. — Ach. 

 Syn. p. 227. — Lichen sepincola, Ehrh. — Hedw. Cr. v. 2. p. 8. 

 t. 2. E. Bot. t. 2386. 



On trees, mostly Firs and Birch, Scotland, especially in the north 

 Highlands. Kinnordy, Forfarshire. On old posts and rails by the sea, 

 near Yarmouth, Mr. Turner. — The apothecia are very rare. — Mr. Dick- 

 son mentions this plant as growing upon stones in the Scotch moun- 

 tains -. I have never seen it except on wood. 



3. C. glduca, Ach. (glaucous Cetraria); thallus membranace- 

 ous smooth somewhat shining sinuated and lobed glaucous-grey 

 above brown beneath, the segments cut and jagged curled as- 

 cending, apothecia marginal elevated chestnut-brown, their bor- 

 der wrinkled. — Ach. Syn. p. 227. — Lichen glaucus, Linn — 

 E.Bot.t. 1066— ZW/. dfusc. t. 25. f. 46 — (3.fallax; thallus 

 white or glaucous on both sides or partially black beneath. 

 Ach. I. c.— C. fallax, Ach. Meth. p. 206.— Lichen fa llax, Web. 

 —Dicks. Cr. Fasc. 1. p. 13. E. Bot. t. 2373.— Dill. Muse, 

 t. 22. f. 58. 



Heathy places on the ground, on rocks and trees ; not uncommon . 



