Lecanora.] LICHENE9- 133 



immersed, at length flat ; with an elevated, entire border. 

 Hook. Eng. Flor. v. 5, p. 173. Lecidea rvfescens, Borr. in 

 Eng. Bot. Supp. I. 2657. Sagedia rufescens, Ach. L. Un. p. 



327. 



On siliceous green sandstone, Cappamore, near Dtmkerron, County 

 of Kerry. Our plant agrees in every particular with the figure and 

 description in English Botany, as well as with a specimen from Mr. 

 Borrer, except in the colour of the thallus and of the disk, the last of 

 which Acharius calls a dusky-black. Under the lens the disk is seen 

 to be rough with elevated cellules ; the lamina proligera is deep, 

 plano-concave, pale, pellucid, full of minute cells ; the disk extends, 

 as in the Acharian figure, beyond the surface of the lamina proli- 

 gera. 



24. LECANORA, Ach. 



Thallus crustaceous, uniform, or scaly and lobed at the mar- 

 gin. Apothecia orbiculate, sessile, their border formed of 

 the thallus, tumid, elevated. 



f Thallus crustaceous, uniform. 

 * Apothecia black, or dark brown. 



1. L. atra, ACH. Thallus tartareous, scarcely determinate, 

 granulato-areolate, whitish-grey ; apothecia numerous, crowded, 

 sessile ; their disk and lamina proligera black, concave, at length 

 plane ; their border whitish, at length crenulate. Ach. L. Un. 

 p. 344. Eng. Bot. t. 949. (not good.) 



On trees and on rocks, especially of the sea-shore ; near Belfast, Mr. 

 Templeton ; in the South of Ireland, common. The thallus is liable 

 to be dispersed. 



2. L. exigua, HOOK. Thallus subtartareous, thin, uneven, 

 of a dull greenish-ash colour ; with a black, thin substratum 

 exceeding at the edges ; apothecia minute, crowded, blackish ; 

 the disk rough, at length convex, and the whitish border at 

 length brownish. Hook. Eng. Flor. v. 5, p. 187. Eng. Bot. t. 

 1849. (the figure on tile.) 



On tiles, near Portmarnock Church, County of Dublin ; also on 

 granite, near Dublin. The disk, dissected under the microscope, is 

 brownish, rough ; the lamina proligera of a very pale-brown, semi- 

 transparent, and has usually dark opaque strife, converging towards 

 the centre of the apothecium, but not exceeding the lamina. 



2. L. periclea, ACH. Substratum of the thallus very thin, 

 dark brown ; scales minute, very thin, snow-white ; apothecia 

 numerous, minute, black; the disk rough; the border snow- 

 white, subpruinose. Ach. L. Un. p. 355. Eng. Bot. . t !850. 



On sandstone rocks, sea-shore, at Derriquin, County of Kerry. The 

 substratum is unnoticed by Acharius ; this species he seems to have 

 found limited to the bark of trees, yet I think it highly probable that 

 our rock plant is the same. 



