238 THE REV. W. А. LEIGHTON ОМ NEW BRITISH LICHENS. 
Spores "016-017 mm. long, ‘007-008 mm. broad. Gelatina hymenea I pale dirty blue. 
Medulla I—. 
Fort Hill! near Fishguard, Pembrokeshire (Sept. 1876). 
LECIDEA IMPONENS, Leight. Thallus obsolete; apothecia black, minute, numerous, 
scattered, sessile, plane or subconcave, margin thin, eventually obliterated ; pale 
bluish-cinerascent within; hymenium and hypothecium hyaline, pale bluish-cine- 
rascent; excipulum horny, bluish-cinerascent, externally darker ; paraphyses thick, 
coherent, apices nigricant ; spores 8, colourless, elliptical, simple. 
Parasitic on Lecanora polytropa (Ehrh.), rare, 1876. 
Spores "014-015 mm. long, "0055 mm. broad. Gelatina hymenea I dirty fuscescent. 
Fort Hill! near Fishguard, Pembrokeshire (Sept. 1876). 
LECIDEA GLAUCOMARIA, Nyl. Thallus obsolete, merely a small irregular, deformed, pale 
nigro-fuscous patch or discoloration, on which are the apothecia; apothecia fusco- 
nigrous, opake, clustered, subinnato-sessile, plane, margin thickish, paler, entire, 
often subflecuose; hymenium fuscescent; paraphyses indistinct, coherent, apices 
incrassate, fusco-nigricant ; hypothecium nigro-fuscous, thin; spores 8, colourless, 
oblongo-ovoid, 3-septate. 
Parasitic on Lecanora glaucoma (Hoffm.), rare, 1876. 
* Gelatina hymenea I pale blue, then vinous red. Spores 021—025 mm. long, 
"008—009 mm. broad ” (Nyl. Obs. Holm. 177, fig. 10; Scand. 245). The apothecia some- 
times form warty agglomerations. Spores "0235 mm. long, "009 mm. broad. 
Not to be confounded with Arthonia glaucomaria, Nyl. (A. varians, Dav.), which 
grows on the apothecia (not on the thallus) of Lecanora glaucoma (Hoffm.) This 
lichen has been found sparingly in France and at Stockholm, but has been now detected 
for the first time in Great Britain. 
Goodwick Bay! Pembrokeshire (Sept. 1876). 
 Ls&CiDEA PARELLARIA, Nyl. (in Flora, 1876, p. 239). Thallus none; apothecia black, 
opake, small, scattered, single or 2 or 8 together, sessile chiefly but not exclusively т 
or near the margins of the areole of the matrix; thallus plane, margin thickish, 
prominent, more or less pruinose ; hypotheciwm nigro-fuscous, thin; paraphyses 
indistinct, conglutinate, apices clavate, nigricant; spores 8, fuscous, lineari-oblong 
or oblong, generally 1-septate, sometimes 2-septate, and sometimes 3-septate in the 
same apothecium ; gelatina hymenea I bluish, then fuscescent. 
Parasitic on Lecanora parella (L.), rare, 1876. 
Spores 011—014 mm. long, "005 mm. broad. This interesting lichen has been found 
once in the West of Ireland, by Mr. Larbalestier in 1876; and 16 now occurs very plenti- 
fully on stone walls about Fishguard, Pembrokeshire (Sept. 1876). 
