98 
NEW BRITISH LICHENS. 
6. Verrucaria elachistophora. Nyl. — Thallus white, unequal, 
rimoso-diffract (perhaps not proper) ; apothecia (probably para- 
sitic) black, slightly emersed, pyrenium entirely black, above 
somewhat impressed; spores 8 nee, colourless, oblongo- ellipsoid, 
simple (or sometimes spuriously 1-septate), 0,007-8 mm. long, 
nearly 0,0035 mm. thick ; paraphyses moderate ; hymenial gela- 
tine not tinged with iodine. 
On quartzose rocks. Kylemore, Galway. 
A peculiar parasitical species, which may belong to the section of 
V. epidermidis. 
I. — Note on Parmelia horrescens, Tayl. 
The plant so named by Taylor, in Mack. FI. Hib. ii., p. 144, has 
hitherto remained unknown in consequence of no authentic speci- 
men having been seen. It is no doubt true that Leighton, in his 
Lich. FI., p. 138, identifies it with Pamielia saxatilis f. furjuracea 
(Schajr.), but as he quoted no authority for this, he was evidently 
guided merely by Taylor’s description. In a series, however, of 
Irish Lichens, in Herb. Brit. Mus., received from Taylor himself, a 
sterile specimen occurs of P. horrescens in his own handwriting. 
This shows it to be entirely referable to Platysma diffusum (Web.), 
with which his diagnosis sufficiently corresponds. Indeed, Taylor 
seems latterly to have become aware of this, for, beneath his own 
name, he writes = Parmelia aleurites , Ach., the true synonymy of 
which has elsewhere been pointed out by Ny lander. There is also 
in Hb. Salwey, a specimen from N. Wales named by Taylor P. 
horrescens , which also = Platysma diffusum, though singularly 
enough Salwey refers to the same plant a specimen of Parmelia 
saxatilis f. furfuracea. Both the Irish and the W elsh plant are 
muscicole, and do not occur on bare rocks, as might be inferred 
from the habitat assigned by Taylor. J. M. C. 
II. — Note on the Synonomy of Parmelia alpicola, Fr. fil. 
In some of the older British Herbaria in Herb. Brit. Mus., this 
plant occurs under different names, e.g., in hb. R. Brown s.n. 
Lichen stygius , and in hb. Sowerby s.n. Lichen encaustus (non Sm.). 
In more recent times also, when distinguished by authors as being 
either a distinct variety or species, it has had various trivial names 
given unto it. Dr. Lindsay, in J Trans. Roy. Soc. Edin,” xxii. 
(1857), has termed it Parmelia encausta v ar. stygioides , in which he 
is followed by Mudd Man., p. 96. Nylander, in his “ Synopsis,” 
pt. ii. (1860), has called it in pt. Parmelia Mougeotii f. discreta, and 
it appears in my “ Enum.,” p. 36, as Parmelia discreta , and in 
“ Leight. Lich. FI.,” p. 127, as Parmelia physodes var. discreta. It 
is also, as proved by a specimen in hb. Carroll, Parmelia stygia f. 
minor , Nyl., in “ Cromb. Enum.,” p. 35. In Th. M. Fries’ “ Lich. 
