504 LICHENACEL. [PERTUSARIA. 
Keswick, Cumberland. Achosragan Hill, Appin, Argyleshire; Craig 
Tulloch, Blair Athole, Perthshire; Glen Callater, Braemar, Aberdeen- 
shire. Kylemore Lake, Connemara, co. Galway. 
18. P. melaleuca Dub. Bot. Gall. t. ii. (1830) p. 673.—Thallus 
subeffuse, thin, smoothish, rimuloso-verrucose, yellowish-cream- 
coloured (K+ yellowish, K(CaCl)+ orange-red). Apothecia in con- 
vexo-depressed, irregular verruce, lacerate at the margins, the 
ostioles depressed, brownish-black, at length pseudo-disciform ; 
spores 2ne, 0,072-75 mm. long, 0,023-25 mm. thick.— Mudd, Man. 
p. 275; Leight. Lich. Fl. p. 240, ed. 3, p. 230; Brit. Angio. Lich. 
p. 29, t. 10. f. 3.—TVhelotrema melaleucum Turn. & Borr. Lich. Br. 
p- 183; Sm. Eng. Fl.v.p.16]. Lichen melaleucus Eng. Bot. xxxv. 
(1818) t. 2461. 
The fertile verruce are for the most part scattered, at times 2-3 con- 
fluent, very rarely crowded, with the ostioles 1 or more, and the margins 
lacerate, inflexed and irregular. They thus appear lecanoroid, and give 
the plant somewhat the aspect of young states of P. Wulfenit. From 
this, however, it is definitely separated by the number of the spores. 
Hab. On smooth trunks of trees in upland wooded situations.— Distr. 
Found only in a few localities in §. and Central England and in N. 
Wales.—B. M.: Shiere, Surrey; St. Leonard’s Forest, Sussex; New 
Forest, Hants; Twycross, Leicestershire; near Barmouth, Merioneth- 
shire. : 
19. P. pustulata Nyl. Act. Soc. Linn. Bord. sér. 3, t. i, (1856) 
p. 441.—Thallus subeffuse, thinnish, subrimose, greyish-white 
(K—, CaCl—). Apothecia several, in small, convex verruce; the 
ostioles punctiform, confluent, blackish; spores 2ne, 0,070-0,120 
mm. long, 0,034-44 mm. thick.—Cromb. Grevillea, xix. p. 59; 
Leight. Angio. Lich. p. 30, t.10. f.4?; Lich. Fl. p. 244, ed. 3, 
p. 234 pro parte; Mudd, Man. p. 275 pro parte; Cromb. Lich. 
Brit. p. 60 pro parte.—Porina pustulata Ach. Lich. Univ. (1810) 
p. 309. 
Often confounded with L. letoplaca, from which, among other cha- 
racters, it differs in the number of the spores. It has more the general 
aspect of P. communis, but apart from the different thalline reactions, 
the verruce are smaller and the ostioles less depressed. There is also a 
leucostomous state (form superpallens Nyl. Flora, 1886, p. 466) which 
has been very sparingly pabberod | in Britain. 
Hab. On trunks of trees in wooded upland situations.—Distr. Local 
and scarce in E., 8. and N. Englund, and N. Wales.—B. M. Epping 
Forest, Essex; New Forest, Hants ; Hinton Abbey, Somersetshire ; Gil- 
garron, Cumberland; Dolgelly, Merionethshire. 
B. Thece pauci- or pluri-spored ; spores blackish. 
20. P. lactescens Mudd, Man. (1861) p. 272 (excl. var. (3).— 
Thallus subdeterminate, thickish, continuous, at length rugoso- 
unequal, rimoso-diffract, greyish or cream-coloured (K + yellow, then 
