porina] pyrenulace^ 339 



Allied to the following, but differing in the character of the spores 

 and in the size and form of the perithecia. 



Hab. On conglomerate fragments of rocks. — B. M. Penzance, 

 Cornwall (the only locality). 



16. P. lucens A. L. Sm. — Thallus purplish- or greyish-brown, 

 thin, tartareous, continuous or minutely cracked, sometimes 

 limited by a black line. Perithecia shining black, moderate in 

 size, sessile, sometimes congregate, prominent, hemispherical, the 

 ostiole a depressed pore ; perithecial wall dimidiate ; paraphyses 

 slender, numerous ; spores 8 in the ascus, broadly elongate-fusi- 

 form-clavate, up to 7- (rarely more-) septate, sometimes a cell 

 with a longitudinal division, colourless, large, 0,038-50 mm. long, 

 0,008-010 mm. thick. — Verrucaria lucens Tayl. in Mackay Fl. 

 Hib. ii. p. 257 (1836) ; Leight. Angioc. Lich. p. 55, t. 24, fig. 2 

 & Lich. Fl. p. 451 ; ed. 3, p. 482. Arthopyrenia lucens Mudd 

 Man. p. 299 (1861). 



Exsicc. Larb. Lich. Hb. n. 280. 



Hah. On rocks and stones. — Distr. Rare iu the Channel Islands, 

 Wales, and S. and W. Ireland. — B. M. Jerbourg, Guernsey ; Trefriw 

 Falls and Conway Falls, Carnarvonshire ; Wastdale Head, Cumberland ; 

 Crogham, Killarney, Kerry ; Killery Bay, Connemara, Galway. 



17. P. interseptula A. L. Sm. — Thallus olivaceous or purplish- 

 brown, thin, efi'use. Perithecia black, small, prominent, sub- 

 globose, sessile, somewhat shining, the ostiole scarcely visible ; 

 perithecial wall dimidiate ; paraphyses slender, numerous, free ; 

 asci elongate, narrowed at both ends, 8-spored ; spores broadly 

 fusiform, 5-septate with occasional somewhat oblique longi- 

 tudinal septa, colourless, 0,018-24 mm. long, 0,006-7 mm. thick. 

 — Verrucaria interseptula Nyl. in Flora Ixiv. p. 453 (1881); 

 Cromb. in Grevillea xii. p. 91. 



Strongly resembling the preceding in form of thallus and peri- 

 thecia, but differing in the size and form of the spores ; the 

 longitudinal septa are more constantly present in one or two of the 

 cells than in P. lucens. 



Hab. On moist siliceous rocks. — B. M. Wastdale, Cumberland. 



117. THELOPSIS Nyl. in Mem. Soc. Sci. Nat. Cherb. iii. 

 p. 194 (1855) ; emend. A. Zahlbr. in Engler & Prantl Nat. 

 Pflanzenf. i. 1*, p. 67 (1903). (PI. 53.) 



Thallus crustaceous, not corticated, thin or scarcely visible. 

 Perithecia surrounded by the thallus, becoming prominent and 

 superficial, or immersed in the thallus ; perithecial wall soft, light- 

 coloured or dark ; paraphyses slender, persistent, unbranched, 

 free ; asci many-spored ; spores ellipsoid or elongate, usually 1-3- 

 septate, rarely simple, colourless. 



Differs from all other genera of the order in the many-spored asci. 



z 2 



