Lecidea.] 



LICHENES. 119 



when the apothecia are largest and most convex ; the apothecia some- 

 times seem to occupy the thallus of other lichens. Dissection shows, 

 beneath a thin black disk, the lamina proligera to be a very narrow 

 layer, striated, whitish-grey, and pellucid, supported on a thick col- 

 lection of black matter. 



12. L. prom inula, Borr, Thallus thin, somewhat tartareous, 

 minutely warty, of a snioke-gre}^ or brownish; apothecia sessile, 

 numerous, minute, black ; the disk tiattish, rough ; the border 

 entire, thick, raised. Bon. in Encj. Bot. S * p. t. 2687, /. 1. 



On rocks near Belfast, Mr. Templeton. County of Kerry ; not 

 uncommon. Varies in the colour of the thallus, its evenness, as well 

 as remarkably in the size of the apothecia. Beneath a brownish-black 

 disk is a lamina proligera pellucid, brownish-grey, and striated, but 

 the brownish-black matter, so commonly filling up the base of the 

 apolhecium in nearly all the preceding species, is here almost 

 wanting. 



13. L. premnea, Ach. Thallus thin, subtartareous, cracked, 

 minutely wrinkled, of a sordid greenish-grey, with a white, 

 finely fibrous border; apothecia slightly convex, sessile; their 

 disk black, rather rough ; their border smooth, at length undu- 

 lated and subcrenate. Ach. L. Un. p. 173. Fries. Lich. Suec. 

 exsicc. No. 26. Dill. Muse. t. 18, /. 3 ? 



On elms, near Belfast, Mr. Templeton. At Derriquin, County of 

 Kerry ; plentiful. Our specimens agree with those of Fries and with 

 the Acharian description. There is no black border to the thallus, as 

 in L. elceochroma, Ach. The apothecia are twice the size of the 

 latter, and their internal structure is different : besides, moisture causes 

 their surface to turn brownish, but of L. elcechroma of a pale blue. 

 Beneath a brownish-black disk, rough with elevations, is a lamina pro- 

 ligera, in a thin, almost colourless, and transparent layer, beneath 

 which again is a thick collection of black matter. 



14. L. elceochroma, Ach. Thallus thin, subtartareous, granu- 

 lated and somewhat wrinkled, pale green, black-edged, crack- 

 ed ; apothecia somewhat immersed, crowded, black, flat, at 

 length convex. Ach. Syn. p. 18. Mugeot and Nestler, No. 746. 

 Lichen parasemus, Eng. Bot. t. 1450. 



On trees ; common. In wet weather the disk has a pale bluish 

 tinge : the greenish tinge of the thallus is sometimes faint, and in other 

 cases deep ; a brownish- olive here is not uncommon. On oaks at Der- 

 riquin the apothecia are in very distinct clusters, each cluster appear- 

 ing to the naked eye as a large apothecium. Dissection of the wet 

 apothecia shows, beneath a pale bluish-brown disk, a thin, transparent, 

 and colourless lamina proligera, resting on much brown matter. 



15. L. parasema, Ach. Thallus thin, submembranaceous, 

 whitish or grey, cracked into smooth, flat, tumid portions, 

 faintly black-edged ; apothecia sessile, scattered, black, convex ; 

 the disk rough; the margins thin. • Ach. Syn. p. 17. Mugeot 

 and Nestler, No. 745. 



On birch trees ; at Cromaglown, near Killarney ; rare. The 



