220 LICHENACEI, [PLATYSMA. 
Well distinguished from Cetraria by the form of the apennog ones, 
though in one section the form of the spermatia indicates some affinity. 
The thallus is at length free, or affixed to the substratum by a few rhizine, 
and is more variable in colour than in Cetraria, When it is membrana-~ 
ceo-dilated, as it sometimes is, it resembles Parmelia, but is separated 
by the spermogones. 
A. Spermatia slightly incrassate or clavate at the obtuse apices. 
a. Thallus erect, becoming free, concolorous on both sides, 
the lacinie elongate. 
1. P. nivale Nyl. Act. Soc. Linn. Bord. sér. 3, 1. (1867) p. 295.— 
Thallus fruticuloso-erect, foliaceo-expanded, sinuato-laciniate, pale 
straw-culoured or ochroleucous, usually tinged brown-ochraceous at 
the base ; lacinis canaliculato-patulous, reticulato-lacunose, dentate 
at the apices (K_,CaCl_). Apothecia adnate on the front of 
the lacinie, subterminal, moderate, yellowish flesh-coloured, the 
margin crenulate; spores small, 0,007-9 mm. long, 0,004-5 mm. 
thick.—Nyl. Syn. i. p. 302, t. 8. f.33; Cromb. Lich. Brit. p. 26; 
Leight. Lich. Fl. p. 99, ed. 3, p. 93.—Cetraria nivalis Gray, Nat. 
Arr. i. p. 483; Hook. Fl. Scot. ii. p. 57; Sm. Eng. Fl. v. p. 221; 
Mudd, Man. p. 78. Lichen nivalis Linn. Sp. Pl. (1753) p. 1145 ; 
Dicks. Crypt. fase. iii. p. 17; With. Arr. ed. 3, iv. p. 60; Eng. Bot. 
t. 1994. Lichenoides lacunosum candidum glabrum, endivie crispe 
facie Dill. Muse. 162, t. 21. f. 564.— Brit. Has.: Leight. n. 43 ; 
Mudd, n. 58; Cromb. n. 24. 
This beautiful species, so characteristic of Arctic and Alpine regions, 
often forms dense tufts, occasionally of considerable size. The apothecia 
do not occur in this country, but the spermogones are occasionally seen. 
They appear as black marginal papille, with sterigmata subsimple, or 
2-3-articulate, and spermatia 0,006-7 mm. long, 0,001 mm. thick, 
Hab. On the ground among mosses and on bare detritus in alpine places. 
— Distr. Rather local, thount lentiful among the Grampians, Scotland, 
chiefly in Braemar.—B. M.: Bea Lawers, Perthshire; Bassies, Clova, 
Forfarshire ; Lochnagar, Ben-naboord, Morrone, Ben Avon, Ben Macdhui, 
Cairngorm, Cairntoul, sources of the Dee, Braemar, Aberdeenshire ; Ben 
Nevis, Inverness-shire, 
2. P. cucullatum Nyl. Act. Soc. Linn. Bord. sér. 3, i. (1867) 
p. 295.—Thallus fruticuloso-erect, foliaceo-complanate, smooth, 
canaliculato-laciniate, pale ochroleucous, usually tinged purplish at 
the base ; laciniz sinuato-divided, the margins connivent, undulate, 
naked, somewhat recurved at the apices (K™, CaCl_). Apothecia 
adnate on the back of the lobes, subterminal, often dilated, pale 
flesh-coloured, the margin thin, or at length excluded; spores 
0,007-10 mm. long, 0,004 mm. thick.—Cromb. Journ. Bot. 1870, 
p. 96; Leight. Lich. Fl. p. 99, ed. 3, p. 94.—Cetraria cucullata 
Mudd, Man. p. 87. Lichen cucullatus Bellard, Obs. Bot. (1788) 
p. 54. Lichenoides marginibus coéuntibus et velut tubulosum Dill. 
Muse. 162, t. 21. f. 56 ».—Brit. Exvs.: Cromb. n. 132. 
In Great Britain this occurs only in small, scattered tufts. It differs 
