ACOTYLEDONS. — LICHENS. Vcrrucavia. 43 



Hab. /3. On slate and stones, frccjuciit, Un-pk. 



2. O. vvlgata, crust between cartilat^inous and mcmbranaeeous 

 somewhat scaly smoothish greenisli white, iijiothecia ses.-^ile 

 long or roundish, waved somewhat shining, with, the disk very 

 narrow. Ack. Syn. Lich. p. 73. E. B. t. IS 11. 



Hab. Bark of trees, common, Efoplc. 



3. O. macularis, crust very thin brownish black, apothecia mi- 

 nute much crowded roundish eliiplical at length rugose irre- 

 gular, disk very narrow. Ack. Syn. Licli. p. 72. 0. cpi~ 

 phega, t. 22S2. 



Hab. On the bark of trees, common, Ilopk. 



Known by the apothecia being so closely crowded as to form largish 

 black spots. 



Sect. II. Hf-teuogemi. Apothecia whs'tviple^ formed vf a so- 

 li lary perlthcclum {or external coverbis) includ'tiig (JieJ'nicti- 

 Jerous mass. 



* Apothecia margined. 

 8. GRAPHIS. 



Universal receptacle crustaceous, spreading, plane, adnate, uni- 

 fornt. Partial recept. elongated, immersed in the thnlliis, 

 which forms a margin on each side the naked. linear disk, not 

 covered by a membrane. (However correct this character 

 may be, the genus does not appear, in hal)!t and general 

 external character, at all different from Opegrapha. 



1. Gr. scrjpta, crust membranaceous smooth somewhat shining 

 v.'hite or grevish brown bordered with black, apothecia half 

 immersed naked flcxuose simple or branched, disk very nar- 

 row, margin formed of the thalliis raised membranaceous. 

 Ach. Syn. Lick. p. Si. E. B. t. 1813 {Opegrapka scripia). 

 Licke?i scriplu^, Ligklf. p. 800. 



Hab. On the smooth bark of trees occasionally. Light f., Ilopk. 



** Apothecia' uilhout amj margin. 

 9. VERRUCARIA. 



Universal receptacle crustaceous, spreading, plane, adnata, uni- 

 form. Partial recept. globoso-hemisphserical, its base im- 

 mersed in tlie thalluSj with a double coat ; exterior subcarti- 

 laginous, thick (black), closing the upper half, tipped with a 

 small prominent orifice ; interior very thin, meudjranaceous, 

 including a subglobose cellular nucleus. 



1. V. maura, crust very thin smooth much cracked very black, 

 apothecia very minute subglobose immersed t!ie extremity 

 prominent umbilicated, nucleus blackish. Ack. Syn. Lick. 

 pA)'r>. E.B.t.2i5Q. 



Hab. Frequent on rocks on the Scolti:<h coast ; as at Lcsic-mouth, 

 coast of Moray ; basaltic rocks at Dunbar, Mr. Borrcr and Hook. 



