J 38 LICHENES. [Lecanora. 



velata, Ach. that I know not to which it should be referred. Dissection 

 shows the lamina proligera to rest on much cortical matter ; to be 

 slightly tinged as well as the disk, to be semitransparent and striated 

 with longitudinal cellules, rather unusually wide : the disk is more 

 opaque and rough with the pruina. 



16. L. tartarea, Ach. Thalliis tartareous, thick, the granu- 

 lations tumid, crowded, pitted, indented or almost lobed, 

 greyish-white; apothecia scattered, large; the disk fla£ or con- 

 vex, often wrinkled, yellowish-brown inclining to flesh-colour; 

 the border thick, inflexed, at length flexuose. Ach. L. Un. p. 

 371. Eng. Bot. t. 156 and t. 1634. 



On siliceous rocks : not uncommon ; also investing mosses or heath 

 in subalpine situations when it becomes the Lichen upsaliensis of Linn. 

 the Lichen frigidus of Eng. Bot. This varies in the thickness of its 

 thallus, and occasionally has a strong resemblance to the preceding. 

 On the full grown disk I do not observe the dense pruina constant in 

 Lec.parella. Dissection shows the disk pale brown, rather opaque, the 

 lamina proligera transparent and colourless, but striated, beneath which 

 again is a layer of opaque yellowish-brown matter which principally 

 imparts colour to the apothecia. When this species occurs on trees, it 

 might seem to constitute the Lecanora Turneri of authors, were it not 

 for the pruina on the disk of the latter as figured in Eng. Bot. t. 857, 

 by which it approaches much nearer to the Lecanora parella. Buds 

 yellowish-grey are not uncommon. 



17. L. citrbia, Ach. Thallus in aggregated leprous scales, 

 somewhat granulated and lobed ; buds powdery, bright lemon 

 coloured, covering the surface ; apothecia scattered, minute ; 

 the disk flat, at length convex, orange coloured ; the border 

 pow dery, elevated, yellow. Ach. L. Un. p. 402. Eng. Bot. 

 t. 1793. 



On walls and rocks ; common : on bark of fir, near Belfast, Mr. 

 Ternpleton. The thallus seems renovated in winter. The apothecia 

 are somewhat immersed in the powder of the buds, they are usually 

 few. The disk is rather thick citron-coloured, the lamina proligera pale, 

 6emipellucid, and striated. 



18. L. vitellina, Ach. Thallus in most minute, somewhat 

 tartareous, sublobate, dispersed, shining, tumid scales, of a 

 tawney-yellow ; apothecia numerous, crowded, minute, flat or 

 concave, at length convex ; the disk of a pale dusky yellow, 

 subpruinose ; the border shining, tumid, of a full yellow, sub- 

 flexuose. Ach. L. Un. p. 403. Eng. Bot. t. 1792. 



On pales, also on basalt, near Belfast, Mr. Ternpleton. The old 

 thallus, at least, presents a thick black substratum, which is much 

 cracked. On old pales the apothecia reach a larger size, and their disk 

 becomes brownish-black. Dissected, the disk appears of a brighter 

 greenish-yellow than the lamina proligera, which is not destitute of a 

 yellowish shade, and is semipellucid, pale, and striated. A variety oc- 

 curs on rocks near Dunkerron, in which the black substratum is the 

 most conspicuous part of the thallus, and fibrous or pulverulent ; above 

 this occur minute, dispersed, golden yellow, shining scales, lobed in a 

 substellate manner; the apothecia are large, their disk usually convex. 



