CETRAKIA. 35 



other; so that Platysma orbatum^yl., Flora,1869, p. 442, rests 

 wholly on the uncertain chemical character. 



16. C. scepincola (Ehrh.) Ach.; thallus sub-membranaceous, 

 foliaceous, few- and short - lobed ; olivaceous - brown ; beneath 

 paler, and without fibrils ; lobes crowded, flattish, undulate and 

 crenate, more or less ascendant, much hidden by the abundant 

 fruit ; apothecia marginal, smallish ; chestnut. Spores ellipsoid, 



-^- mic. Spermatia as in C. ciliaris. Ach. L. U. p. 507. 



Fr. L. E. p. 39. Platysma, Nyl. Syn. 1, p. 308. 



b. chlorophylla, Wahl.; larger, and paler; the irregularly 

 laciniate lobes with white-sorediate edges ; scarcely fertile. 



On twigs, Arctic America (Richardson], Hooker 1. c. 1823. 

 Branches of dwarf firs in the sub-alpine region of the White 

 Mountains, Tuckerman. Cold swamp, Hawley, Hampshire, 



Mass., Porter. b, Oregon, Dr. Lyall. Coast of California, 



Eolander. 



b. Stock of C. glauca. 



17. C. lacunosa, Ach.; thallus cartilagineous- coriaceous, 

 foliaceous, the crowded lobes more or less dilated and rounded, 

 and deeply reticulate-lacunose, with ascendant, lacero-crenate, 

 smooth margins; glaucous above; whitish, or here and there now 

 blackening below ; apofchecia (abundant) sub-terminal, ample, 

 at length a little elevated ; disk chestnut (often perforated at 

 the centre) ; margin entire. Spores rounded-ellipsoid, - - mic. 



-4jj 



Spermatia oblong, thickening gradually towards one end. 



Ach. L. U.p. 508. Tucker m. Syn. N. E. p. 16; Exs. n. 6, 61. 

 Platysma, Nyl. Syn. I, p. 314. 



b. stenophylla ; lobes more lax, narrow -linear, elongated, 

 channelled ; white beneath ; apothecia terminal. 



Trees, North-west coast (Menzies), Ach. Meth. 1803. Very 

 common on trees and rails through the Northern and Middle 

 States, and, along the mountains, southward ; Halsey ; Ravenel, 



etc. b, simulating now the habit of large states of Hamalina 



calicaris and now of Evernia furfuracea, California ; Bolander. 

 The var. laciniatum, Nyl. Flora, 1869, p. 442, from California, 

 cannot be cited, as it has no character. 



18. C. glauca (L.) Ach.; thallus membranaceous, foliaceous, 

 sinuate-lobate or irregularly lacerate-laciniate ; glaucous, black- 



