ADDENDA. 259 



pearance of scales, that perhaps this Lichen is better arranged under 

 Endocarpon than Verrucaria. 



Page 106, before Opegrapha scripta, insert 



O. saxigena. Thallus leproso-tartareous, thin, rust-brown, 

 slightly cracked \vhen dry, subgelatinous when moist, indeter- 

 minate ; buds pale- green, leproso-pulverulent. Apothecia ses- 

 sile, prominent, grouped; the disk narrow; the border tumid, 

 uneven, somewhat broken, shining. 



On mural rocks, in moist situations, Dunkerron. Although several 

 OpegraphcB that usually occur on trees are found on rocks likewise in 

 the County of Kerry, and in such case somewhat modified in appear- 

 ance, yet to no other known species can the characters, especially those 

 drawn from the buds of the present plant, be referred. The thin 

 brownish patches are often 3 or 4 inches in diameter, and conspicuous 

 from the green powder about the apothecia ; this which constitutes the 

 buds is absent in apparently aged portions of the thallus, and most 

 abundant in spring about the newer apothecia. The lirellca are at first 

 punctiform and roundish, at length elongate, waved, and not unfre- 

 tjuently branched. The disk is less shining than the ragged border, 

 whose continuity is repeatedly broken. A transverse section, under a 

 good lens, shows the disk to be covered with a black pruina, the lamina 

 pale, semipellucid, striated, occupying but a narrow 7 groove in the upper 

 part of the black tartareous matter of which the lirellce are principally 

 composed. 



Page 107, after Collema nigrum, insert 



Decandolle, in his Flora Fran9aise, doubts the generic character. I 

 have recently observed states that indicate an identity with, Parmelia 

 plumbea, var. . microphytta, of this work. 



Page 1C 9, after Collema fragile, insert 



Very lately I have met with apothecia more aged than those de- 

 scribed. In a dry state they appear sessile, but thoroughly moistened, 

 the thallodal covering swells so as nearly to close over the disk, and 

 the border of the apothecia gradually subsides into the level of the 

 thallus. The disk is brownish-olive, pruinose ; the lamina striated, 

 whitish above, of a pale rose-colour beneath. 



Page 119, before Lecidea premnea, insert 



L. latens. Thallus indeterminate, very thin, leproso-tarta- 

 reous, slightly cracked, somewhat uneven, of a pale aeruginous 

 green, pale-brown about the centre. Apothecia minute, scat- 

 tered, purplish-black, flat, at length convex, and excluding the 

 border. 



On stones, in dark recesses of a bank facing the north, in the wood 

 at the Dargle, County of Wicklow. A few black points scarcely visible 

 on the stone, apparently discoloured by powdered clay, constitute all 

 that this Lichen presents to the naked eye. Moistened and under the 

 lens, it exhibits a very thin pale verdigris green crust, which is mottled 

 with brown, and altogether brown about the apothecia, where too it is 

 somewhat thickened. The apothecia are of different sizes the largest, 

 however, scarcely distinct to the naked eye, except by their brilliant 



