THELOTREMA.] LECANO-LECIDEEI. 616 



disc dilated, the thallinc 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. 



Hah. On trunks of old trees in -wooded maritime and mountainous 

 tracts. — Di.<:fr. Only a few localities in S. and X. England, N. Wales, 

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

 Hants ; Xannau, Dolgeliy, Merionethshire ; Wark, Northumberland. 

 Loch Creran, Argyleshire. Glenstale, co. Tipperarv ; Derricuiutry, Kil- 

 larnej-, co. Kerr}-. 



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

 or less scattered, occasionally evanescent, otherwise as in the 

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

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

 t. 12. f. 2 ; Mudd, Man. p. 278. Yar. scutelliforme Tavl. in Mack. 

 EI. 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-2nie. 



Hab. On rocks in maritime and upland situations. — Dintr. Sparingly 

 in X. "\Yales. X. England, the S.W. Highlands of Scotland, and W. 

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

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

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

 Galway. 



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

 p. -iiQ ; Xvl. Flora, 1804, p. 491. — -Thallus macular, somewhat 

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

 thecia erumpeut, small, colourless, the thalline margin slightly 

 prominent, the proper mai'giu ofteu white-pulverulent ; spores 8nse, 

 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.— 5/-i<. Exs. : Cromb. 

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



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

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

 tilmy thaUus and smaller apothecia ; but its real affinity is with T. bi- 

 cinctulum Xyl., an Austi-alasian species, from which it differs chiefly in 

 the larger spores. 



Hab. On smooth bark of trees in shady upland situations. — Dktr. 

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

 larney, and Lough Inchiquin, co. Keriy ; Lough Derrj'clare and Holly 

 Island, Lough Inagh, Connemara, co. Galway. 



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

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

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

 obsolete ; hypothallus white. Apothecia urceolato-impressed, vrith 

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



