92 LICHENES. [rerrucatia. 



On the old walls of Dunkerron castle ; and on maritime rocks. 

 The perithecium passes under the nucleus. Apothecia when growing 

 on mortar usually partially immersed. The thallus sometimes evanes- 

 cent, yet like a whitish stain on the rock : the nucleus pale brown, 

 gelatinous when wet. The tops of the apothecia often shining, though 

 minutely wrinkled. 



21. V. lithina, ACH. Thallus thin, tartareous, areolato-rugose, 

 greyish-green ; apothecia minute, partially immersed in the 

 elevated portions of the thallus on which each is placed, 

 brownish-black ; pore on their summits marginate, often wide. 

 Ach.Lich. Un.p. 287. 



On shaded siliceous rocks at Derriquin, County of Kerry. The 

 thallus may be considered as divided into numerous, minute, tumid, 

 wrinkled tartareous scales, so closely joined that the surface seems 

 continuous, yet under the lens it appears areolate and the scales them- 

 selves are sometimes split ; greyish-green when dry, greener when 

 moist ; having a thin faint white border. Apothecia each on a proper 

 portion of the thallus, globoso-conical, umbilicate, evenly scattered, 

 very minute, yet distinct to the naked eye. Nucleus pale, gelatinous 

 when moist, and then protruding out of the pore. Perithecium pass- 

 ing under the nucleus. 



22. V. epipolcea, ACH. Thallus indeterminate, leproso-tar- 

 tareous, thin, somewhat powdery, greyish-white ; apothecia 

 large, sessile, hemispherical, black, papillose or porous, some- 

 what pruinose. Ach. Lich. Un. p. 285. Eng. Bot. Supp. t. 

 2647, /. 3. 



On limestone at Dunkerron ; common. The thallus usually suf- 

 fused with a reddish hue, slightly and minutely cracked, but when thin 

 continuous. Apothecia among the largest in this genus, often one- 

 fifteenth of an inch, roughish. Nucleus globose, minute, shrivelled 

 when dry, when moistened swelling, filling the cavity of the perithe- 

 cium, pale, hyaline ; contained in a proper, whitish, closely investing 

 tegument. The perithecium does not pass beneath the nucleus. The 

 apothecia slightly immersed beneath the surface. 



23. V. Dufourii, DE CAND. Thallus determinate, subtarta- 

 reous, arenaceo-pulverulent on the surface, of a dusky greenish- 

 grey, continuous ; apothecia large, subsessile, hemispherical, 

 black, porous on the summit; nucleus with a proper black peri- 

 thecium. De Cand. Fl. Fr. ed. 2, v. 2, 318. Eng. Bot. t. 2791, 

 V. pyrenophora, Ach. L. Un. p. 285. 



On limestone rocks, and on the walls of Dunkerron castle, County 

 of Kerry. Patch from one to six or seven inches in breadth, conspi- 

 cuous by the evenly scattered large apothecia. The thallus has a nar- 

 row dark brown or black limit, more evident in contact with other 

 lichens ; by moisture the surface becomes greener ; this arises from 

 (as seen by a lens) the parenchymatous green substance becoming 

 more visible among the minute greyish grains of the superior layer ; 

 when dry the surface appears harshly-powdery as if sanded ; beneath 

 the green layer is another more compact and white. Apothecia im- 

 mersed by about one-fourth of their entire height below the surface of 

 the thallus and penetrating slightly the limestone beneath ; having a 



