Rev. T. Salwey's List of Lichens gathered in Wales. 261 



may be distinguished from smaragdulum, 1st, by its mode of growth ; 

 2ndly, by the particular habitat which each of these species affects. 

 The rufo-virescens, from the scales of the thallus being usually col- 

 lected together into a close-set areolate crust, forms a well-defined 

 conspicuous object which arrests the eye at some distance. It is also 

 of a darker colour than the smaragdulum, being usually of a brown 

 reddish green, whereas the smaragdulum is of a pale fawn-colour. 

 3rdly, the rufo-virescens usually grows upon the smooth perpendi- 

 cular face of the stone ; but the smaragdulum upon the broken edges 

 of the fracture of the stones in the walls, and can only be chipped 

 off in small bits in the direction of the strata. 



4. Parmelia rugosa. This grows not uncommonly about Barmouth, 

 but is scarce in fruit. I have gathered however fine specimens in 

 that state on the wall of a field under a w^ood to the west of the 

 old mill at Ty Gwyn, and also between Crafnaut and Cwm Bychan, 

 on a low wall on the right-hand side of the road. 



5. Cornicularia bicolor. Amongst the stones under the rocks at Llyn 

 Bodlyn. 



6. ■ lanata. Sent to me by Mr. Ralfs from Cader Idris. 



7. Urceolaria cinerea. Common, particularly about the borders of 

 lakes. U. calcarea is found only where the rocks are of a calcareous 

 nature. 



8. Nephroma resupinata, j3 papyracea, Ach. and Wahl. On stones 

 and mosses, and upon the mossy trunks of trees : not uncommon. 

 I have hitherto regarded this plant as the parilis of Acharius, and 



I still believe it to be the same as the plant described and figured in 

 the ' Eng. Bot.' under that name. After much examination, however, 

 and in the absence of authentic specimens from Acharius of the Swe- 

 dish plant, I must confess my belief, that whether the true parilis or 

 not, our plant is that which Acharius has described as the " resupinata, 

 ft papyracea ;" Wahlenberg as the " Peltidea resupinata, ft papyracea ;" 

 and Dillenius, xxviii. 105. p. 206, Edinb. ed. 1811, as the " Lictie- 

 noides fuscum, var . farinosa et crispa." My fi'iend Dr. Taylor has 

 always contended that what I have sent him as the parilis is only 

 " a mountain state of the resupinata." Acharius, who in his ' Lich. 

 Univ.' in 1810 described the parilis as a native of Sweden and En- 

 gland, in his ' Syn.' in 1814 speaks of it only as a Swedish plant, 

 as if he had given up the claim of our English plant to be the parilis ; 

 yet he does not refer to it under the ft papyracea of that work, so that 

 he leaves us in doubt what at that time he considered the parilis of 

 the ' Eng. Bot.' to be. Dillenius, Acharius and Wahlenberg all de- 

 scribe a variety of resupinata which pretty accurately agrees with the 

 plant I have hitherto regarded as parilis, and w^hich I have indeed 

 no doubt is the /)ar«7«5 of 'Eng. Bot.' Dillenius says in the place 

 above cited, " Sunt mihi hujus speciei exemplaria absque peltis cum 

 marginibus crispis et farinosis B : et habeo alia ubi non tantum mar- 

 gines, sed et ipsa folia verrucis farinosis obsita, C, in quibus fohorum 

 superficiem nonnihil lacunosam observo ; eadem tamen planta est, 

 tota facie, colore et substantia utrinque congruente." I would here 



