146 LICHENES. [Gpegrapha. 



O. lithyrga, O. calcarea, O. tridens, (3> and O. Persoonii, (excl. 

 var. c.) Ach. Syn. 



On rocks, walls, sandstone, old mortar, &c. — Mr. Borrer thinks this 

 should be united to O. varia. — See Mr. Borrer's remarks under Opegra- 

 phci tesserata, in E. Bot. Suppl, t. 2632. /. 2. 



10. O. cerebrina, De Cand. (tumid-crusted Opegraphci); crust 

 tartareous continuous very white, apotliecia naked promi- 

 nent short obtuse simple or variously divided and deformed their 

 border broad inflexed at length expanding and obliterated. 

 Borr. — De Cand. Fl. Fr. v. 2. p. 312. Chev. Hist, des Hypox. 

 p. 57. t. 12. /. 4. Borr. in E. Bot. Suppl. t. 2632./. l.—Lecidea 

 plocina, Ach. Syn. p. 16. — Patellaria cerebrina, Dubis. 



Rare; on calcareous stone, Mr. Dickson. North of England, 

 Rev. J. Harriman. — This appears to be a very little known Lichen; and, 

 out of England, according to Mr. Borrer, only to have been found in 

 the Pyrenees. Its crust is unequally thick, pure white. Apothecia, or 

 Urellte, full black, sometimes polished, not very numerous, mostly in 

 clusters, occasionally solitary, at first oblong, or almost orbicular, with 

 an inflexed, convex, even border closed over the disk, soon cloven at one 

 or both ends, becoming triangular, quadrangular or more irregular in 

 figure, and the border expanding and disclosing the disk, often so widely 

 as to give to the lirellce a close resemblance to an irregular patellula, with 

 sometimes a prominent and crenulate, sometimes an obliterated border. 

 Often, too, the lirellce become confluent, and the clusters assume the 

 appearance of the imperfect trices of a Gyrophora : — their base is sunk in 

 the crust and even into the stone beneath. Borr. 



11. O. tesserata, De Cand. (tessellated Opegraphci) ; crust tarta- 

 reous areolate brownish-grey, apothecia naked prominent short 

 obtuse simple or slightly divided with a broad inflexed margin. 

 Borr. — De Cand. Fl. Fr. v. 2. p. 313. Chev. Hist, des Hypox. 

 p.5\.t.l\.f.\. Borr. in E.Bot. Suppl. t. 2632./. 2,— O.petrcea, 

 Ach. Syn. p. 72. 



Hocks, Scotland, Acharius. On Holwick Scaur, by the Tees, York- 

 shire, Mr. IV. Robertson. — The lirellce of this species considerably re- 

 semble those of O. Persoonii, but the urceolate crust distinguishes it at 

 once both from that plant and from O. saxatilis : — " This crust forms 

 patches of considerable extent, and is said to be bordered with a black 

 line when perfect. It is of a structure, not uncommon in various 

 genera of Lichens, but not hitherto observed in any other Opegrapha, 

 being composed of granulations, at first scattered and convex, afterwards 

 crowded together and forming small angular areolce, irregular in shape 

 and size, the interstices of which are barely visible to the naked eye ; 

 the genera] surface is rather uneven, unpolished, brownish-grey with 

 a tinge of red, the internal substance white." Borr. 



** Apothecia with a raised accessory border formed of the crust. 

 Graphis. Ach. 



12. O. elegans, Sm. (elegant grooved Opegraphci); crust or- 

 bicular granulated white, apotliecia immersed scattered divari- 

 cated mostly simple with a grooved border and an accessory one 

 formed of the crust. Borr. in E. Bot. £ 1 8 1 2. — Graphis elegans, 

 Ach, Syn. p. 85. 



