THELOTREMA.] LECANO-LECIDEEI. 515 



disc dilated, the thalline margin tumid, rugose. Cromb. Grevillea, 

 xix. p. 60. 



A good variety apparently constant to the characters given. The 

 apothecia are often here and there aggregate in small protuberant 

 groups. 



Hub. On trunks of old trees in wooded maritime and mountainous 

 tracts. Distr. Only a few localities in S. and N. England, N. Wales, 

 the S.W. Highlands of Scotland, and S. Ireland. B. M. : New Forest, 

 Hants ; Nannau, Dolgelly, Merionethshire ; Wark, Northumberland. 

 Loch Creran, Argyleshire. Glenstale, co. Tipperary ; Derricuintry, Kil- 

 larney, co. Kerry. 



Form rupestre Cromb. Lich. Brit. (1878) p. 61. Thallus more 

 or less scattered, occasionally evanescent, otherwise as in the 

 variety. Leight. Lich. Fl. p. 248, ed. 3, p. 238. Var. rupestre 

 Turn. & Borr. Lich. Br. (1839) p. 180 ; Leight. Angio. Lich. p. 32, 

 t. 12. f. 2 ; Mudd, Man. p. 278. Var. scutelliforme Tayl. in Mack. 

 Fl. Hib. ii. p. 103. 



A depauperate state rather than a distinct form, resulting no doubt 

 from the habitat. The thallus is at times subochraceous as noted by 

 Leighton, who, however, erroneously says that the spores are l-2nae. 



Hab. On rocks in maritime and upland situations. Distr. Sparingly 

 in N. Wales, N. England, the S.W. Highlands of Scotland, and W. 

 Ireland. B. M. : Llyn Bodlyn and Cammlan Valley, Merionethshire; 

 Teesdale, Durham. Island of Lismore, Argyleshire. Kenmare Road, 

 Killarney, co. Kerry ; Kylemore and Doughruagh Mts., Connemara, co. 

 Galway. 



2. T. subtile Tuck. Americ. Journ. Sc. & Art, t. xxv. (1858) 

 p. 426; Nyl. Flora, 1864, p. 491. Thallus macular, somewhat 

 shining, cream-coloured or whitish (K -f yellowish, CaCl ). Apo- 

 thecia erumpent, small, colourless, the thalline margin slightly 

 prominent, the proper margin often white-pulverulent ; spores 8nae, 

 oblong, 10-13-locular, colourless, 0,040-56 mm. long, 0,009-0,010 

 mm. thick. Carroll, Journ. Bot. 1865, p. 289 ; Cromb. Lich. Brit, 

 p. 61 ; Leight. Lich. Fl. p. 248, ed. 3, p. 239. Brit. Exs. : Cromb. 

 n. 169 ; Larbal. Lich. Herb. n. 62. 



An interesting plant, elsewhere found only in the United States of 

 America. At first sight it looks as if it were only T. lepadinum with 

 filmy thallus and smaller apothecia ; but its real affinity is with T. bi- 

 cinctulum Nyl., an Australasian species, from which it differs chiefly in 

 the larger spores. 



Hab. On smooth bark of trees in shady upland situations. Distr. 

 Only sparingly in W. Ireland. B. M. : Turk Mt., Cromaglown, Kil- 

 larney, and Lough luchiquin, co. Kerry ; Lough Derryelare and Holly 

 Island, Lough Inagh, Connemara, co. Galway. 



66. UBCEOLARIA Ach. Prodr. (1798) p. 30 (ut tribus) ; Meth. 

 p. 141 (ut genus) pro parte ; NyL Mem. Soc. Cherb. iii. (1855) 

 p. 180. Thallus crustaceous, continuous or areolate, very rarely 

 obsolete ; hypothallus white. Apothecia urceolato-impressed, with 

 .a proper and a thalline margin ; hypothecium brown or blackish ; 



