504 LICHENACEI. [PEETtTSAKIA. 



Keswick, Cumberland. Achosragan Hill, Appin, Argyleshire ; Craig 

 Tulloch, Blair Athole, Perthshire ; Glen Callater, Braeinar, Aberdeen- 

 shire. Kylemore Lake, Connemara, co. Galway. 



18. P. melaleuca Dub. Bot. Gall. t. ii. (1830) p. 673. Thallus 

 subeffuse, tbin, smootbish, rimuloso-verrucose, yellowish-cream- 

 coloured (K-f yellowish, K(CaCl) + orange-red). Apothecia in con- 

 vexo-depressed, irregular verruca3, lacerate at the margins, the 

 ostioles depressed, brownish-black, at length pseudo-disciform ; 

 spores 2nae, 0,072-75 mm. long, 0,023-25 mm. thick. Mudd, Man. 

 p. 275; Leight. Lich. El. p. 240, ed. 3, p. 230 ; Brit. Angio. Lich. 

 p. 29, t. 10. f. 3.Thelotrema melaleucum Turn. & Borr. Lich. Br. 

 p. 183 ; Sm. Eng. El. v. p. 161 . Lichen melaleucus Eng. Bot. xxxv. 

 (1813) t. 2461. 



The fertile verrucse 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. Wulfenii. From 

 this, however, it is definitely separated by the number of the spores. 



Hob. On smooth trunks of trees in upland wooded situations. Distr. 

 Found only in a few localities in S. 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. pnstulata Nyl. Act. Soc. Linn. Bord. ser. 3, t. i. (1856) 

 p. 441. Thallus subeffuse, tbinnish, subrimose, greyish- white 

 (K , CaCl ). Apothecia several, in small, convex verrucae ; the 

 ostioles punctiform, confluent, blackish; spores 2nae, 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? ; Licb. El. 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. leiopltica, 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 verruca? are smaller and the ostioles less depressed. There is also a 

 leucostonious state (form superpallens Nyl. Flora, 1886, p. 466) which 

 has been very sparingly gathered in Britain. 



Hob. On trunks of trees in wooded upland situations. Distr. Local 

 and scarce in E., S. and N. England, and N. Wales. B. M. Eppiug 

 Forest, Essex; New Forest, Hants ; Hinton Abbey, Somersetshire ; Gil- 

 garron, Cumberland ; Dolgelly, Merionethshire. 



B. Thecae pauci- or pluri-spored ; spores blackish. 



20. P. lactescens Mudd, Man. (1861) p. 272 (excl. var. ft). 

 Thallus subdeterminate, thickish, continuous, at length rugoso- 

 unequal, rimoso-diffract, greyish or cream-coloured (K + yeDow, then 



