PERTUSARIA | PERTUSARIACEE 367 
Hab. On rocks in maritime and mountainous districts.— Distr. 
Rare throughout the British Isles, though fairly plentiful where it 
occurs.—B. M. Jersey; Pentire, Kynance and Lamorna, Cornwall ; 
Harlech, Barmouth, Aberdovey and near Dolgelly, Mericneth; Holy- 
head, Anglesea; Airds, Appin, Argyll; Craig Calliach, Perthshire ; 
Lambay Island, Dublin. 
Form microstictica Cromb. Monogr. i. p. 502.—Thallus 
sprinkled with minute brownish papille.—Lichen microsticticus 
Sm. Engl. Bot. t. 2243 (1811). Isidium microsticticum Turn. & 
Borr. ex Hook. Fl. Scot. ii. p. 66 (1821) & Lich. Brit. p. 94 ; 
S. F. Gray Nat. Arr. i. p. 774; Hook. in Sm. Engl. Fil. v. 
. 231. 
‘i Exsicc. Leight. nos. 280, 342. 
Scarcely to be considered as a true form, as the same type of 
small brown papille are occasionally present in P. concreta. When 
they are abraded they leave a minute white dot on the thallus. 
Hab. On rocks in maritime and mountainous regions.—Distr. 
Rare in the Channel Islands, N. Wales and S.W. Ireland (fide 
Crombie).—B. M. Barmouth, Merioneth. 
Form variolosa Mudd Man. p. 271 (1861).—The thalline 
verruce sterile, sorediate.—Cromb. in Grevillea xix. p. 59 & 
Monogr. i. p. 502. 
Exsicc. Leight. n. 341. 
The pulverulent verruce are crowded and are more regular, as 
well as generally smaller, than in the species, but the affinity is easily 
recognized by the reaction with potash. 
Hab. On rocks in maritime districts.—Dist7v. Rare in N. Wales 
and W. Ireland.—B. M. Dolgelly, Merioneth; Achill Island, Mayo. 
17. P. concreta Nyl. in Mém. Soc. Sci. Nat. Cherb. v. p. 117 
(1857) & in Flora lix. p. 233 (1876).—Thallus determinate, 
thickish, unequal or generally plane, cracked-areolate, whitish 
(K + yellow, then red). Apothecia immersed in the areolz, the 
dise punctiform then somewhat exposed, flesh-coloured to blackish ; 
spores 2 in the ascus, 115-250 yp long, 60-80 » thick.—Cromb. 
in Grevillea v. p. 25 (1876) & Monogr. 1. p. 505; Leight. Lich. FI. 
ed. 3, p. 227. 
Exsicc. Larb. Lich. Hb. n. 27. 
Originally described from the Eastern Pyrenees, and considered by 
Nylander to be the specific form of Isidiwm Westringwi. It differs 
from P. ceuthocarpa in the absence of pronounced verruce, minute 
papille are often present. Fertile specimens are very rare; in one 
from Clare Island the spores were barely mature, but the largest 
measured only 175 p x 55 p. 
Hab. On rocks in maritime districts.—Dzstr. Local but somewhat 
abundant in W. Ireland.—B. M. Letterfrack, Connemara, Galway ; 
Clare Island, Achill Island and Mallaranny, Achill, Mayo. 
