132 LICHENES. [Urceolaria. 



23. Urceolaria, Ach. 



Thallus crustaceous, uniform. Apothecia orbiculate, immersed 

 in the thallus ; the disk concave ; the border formed of the 

 crust. 



1. U. scruposa, Ach. Thallus tartareous, rugoso- plicate, 

 granulate, cracked, grey ; apothecia urceolate, immersed ; the 

 disk black, pruinose ; the thallodal border inflexed, crenate. 

 Ach. Lich. Un. p. 338. Eng. Bot. t. 94. 



On siliceous rocks, at Dunkerron ; on the sand hills at Portmar- 

 nock, near Dublin, abundant. Disk pruinose ; lamina proligera thin, 

 horny, with dark opaque vertical strice. 



2. U. eontorta, Ach. Thallus of distinct, clustered, tumid, 

 light-greenish scales, with elevated whitish edges ; apothecia 

 usually single, immersed in the scales ; the disk brownish-black, 

 pruinose ; the thallodal border whitish and powdery. U. Hoff- 

 manni, ft. eontorta, Ach. L. Un. p. 333. Eng. Bot. 1. 1940, (the 

 greenish figure.) 



On limestone, at Portmarnock and Feltrim Hill, near Dublin ; 

 on basalt, near Belfast, Mr. Templeton. On granite, near Dublin. 



3. U. calcarea, Ach. Thallus tartareous, powdery, cracked, 

 even, determinate; the border narrow, of a lead-blue; apo- 

 thecia immersed, numerous, minute, round, at length oblong, 

 angular, and crooked ; the disk black, pruinose. Ach. L. Un. 

 p. 340. Eng. Bot. t. 820. 



On limestone ; common. 



4. U. cinerea, Ach. Thallus tartareous, cracked, grey, 

 rugged, determinate ; the border broad, greenish, undulated ; 

 apothecia immersed, numerous, slightly concave, black, pru- 

 inose ; thallodal margin elevated. Ach. L. Un. p. 336. Eng. 

 Bot.t. 1751. 



On siliceous rocks (never on calcareous) ; common. The surface of 

 the thallus is more rugged and not so white as in the preceding ; the 

 border is much broader and of a different colour ; the apothecia are 

 larger, besides it does not occur on limestone. 



5. U. Acharii, Ach. Thallus tartareous, smooth, cracked, 

 white, with a snow-white thin border; apothecia immersed ; the 

 disk of a light flesh colour; the thallodal border tumid. Ach. 

 L. Un. p. 331. ft. thallus of a pale brick colour. Eng. Bot. 

 t. 1087. 



On rocks near the water's edge, Finnehy River. (3. on drier rocks, 

 exposed to the sun : neither variety is ever seen on limestone : the 

 substratum of the lamina proligera is apt to turn from white to dark- 

 brown. 



6. U. rufescens, Hook. Thallus indeterminate, thin, tarta- 

 reous, tessellated, of a smoke-grey ; apothecia small, dark-grey, 



