PERTUSARIA.] LECANO-LECIDEEI, 509 



27. P. gyrocheila Xyl. Flora, 18G5, p. 354.— Thallus dcter- 

 miiiate, subgraiiuloso-uncqual, rimoso-diffract, greyish (K + yellow, 

 CaCl — ). Apothccia in thelotrcmoid tubercles, simple or at 

 length subgyrose, the thalline margin thick, subgyrose ; epithecium 

 glypholeceine, hymenium pale ; spores 0,0<;S-70 mm. long, 0,030- 

 50 mm. thick ; hymonial gelatine and the thecaj bluish -with 

 iodine. — Carroll, Journ. Bot. ISGG, p. 23 ; Cromb. Lich. Brit. p. 61 ; 

 Leight. Lich. Fl. p. 241, ed. 3, p. 232. 



A very distinct species well characterized by the peculiar form of the 

 fructificatiou. The thallus is small, with the fertile verruca? more or less 

 scattered and crateriform. The very few specimens gathered are only 

 sparing fertile. 



Hab. On mica-pchist rocks in an alpine situation. — Distr. Extremely 

 local and scarce on one of the S. Grampians, Scotland. — B. M. : Summit 

 of Ben Lawers, Perthshire. 



h. Spores normally 4nce. 



28. P. leioplaca Schaer. Spicil. (1823) p. 60 : ^'yl. Lich. Scaud. 

 p. 181. — Thallus subdeterminate, thin or rarely submoderate, 

 smooth or ruguloso-uncqual, rimose, milk-white, yellowish-white 

 or whitish (K— or f-t- yellowish). Apothecia in somewhat convex, 

 smooth, usually discrete verrucse, the ostioles solitary or few 

 (1-3-5), punctiform, dark ; spores usually 4nce (but variable in 

 number), oblongo-ellipsoid or subellipsoid, 0,042-75 mm. long, 

 0,020-38 mm. thick.— Mudd, Man. p. 267 : Cromb. Lich. Brit, 

 p. 60 : Leight. Lich. Fl. p. 244. ed. 3. p. 234. — Porina hioplacu 

 Ach. Yet. Ak. Haudl. 1809, p. 159 : Lich. Lniv. p. 309, t. 7. f. 2. 

 Pertusaria communis var. ^. leioplaca Turn. & Borr. Lich. Br. 

 p. 197.— -SrfV. Exs. Leight. n. 230 : Mudd, nos. 265, 267. 



The thaUus varies somewhat in thickness, becoming at times subcon- 

 crescent, when the verrucse are more prominent. As noted bv Th. M. 

 Fries (Lich. Scand. p. 316), the chemical reaction varies accurding to the 

 colom- of the thallus, beiug little (or not) distinct when it is dealbate. 

 The apothecia are also variable, usually solitary, rarely 3 or -5 in the 

 verrucae, with the spores at times 3-5-6-8nae, very rarely inse (in a 

 single British specimen). 



Hnb. Ou the trunks of trees in maritime and upland districts. — Distr. 

 In most parts of Great Britain, no doubt also of Ireland : not seen from 

 the Channel Islands. — B. M. : Xeai- Highbeach. Epping Forest; lorhtham, 

 Kent ; St. Leonard's Forest, Sussex : Shanklin. Isle of Wight : New 

 Forest, Hants ; Lustleigh, S. Devon : Withiel. Cornwall ; near Ciren- 

 cester, Gloucestershire ; Woodbury Hill and Malvern. Worcestershire ; 

 GopsaU Park, Leicestershire ; Gloddaeth, Carnai-vonshire ; Bettrws-v- 

 coed, Denbighshu-e : Island of Anglesea : Xewton Wood and Sowerdale 

 Cleveland, Yorkshire : Lamplugh, Cumberland. Barcaldiue, Aro-yle- 

 shire ; Craig Calliach, Ealhn and Falls of Moness, Aberfeldy, Perthshire ; 

 Moor of MoiTone, Braemar, Aberdeenshire : Glen Xevis, Inverness-shire. 

 Enniskean, co. Cork ; McCarthy's Island and Lpper Lake, Killarnev, co. 

 KeiTy ; Eenvyle Wood, Connemara, co. Galway. 



