OF GREAT BRITAIN. 7 



Sub-tribe II. Pannariei. 



Gonidial stratum of thallus consisting of granula gonima. = 

 Pannaria. 



Sub-tribe III. Amphilomei. 

 Thallus white, granuloso-pulverulent. = Amphiloma. 



Sub-tribe IV. Squamariei. 

 Spores simple. = Squamaria. 



Sub-tribe V. Placodei. 

 Spores polari-bilocular. = Plaoodium. 



SUB-TRIBE VI. EULECANOREI. 



Apothecia internally colourless : spores 8 or numerous, simple 

 or variously divided, colourless or fuscous. = Lecanora. 



Apothecia tuberculoso-lecanorine ; hypothecium black ; spores 

 fusiform, 3-septate. = Dirina. 



Sub-tribe VII. Pertusariei. 



Apothecia endocarpoid, or lecanoroid or variolaroid ; spores 

 1-2-4-8, simple, very large, ellipsoid, with a thick episporium. = 

 Pertusaria. 



Apothecia erumpent, rotundato-dififormed ; spores 1-2, mur.ili- 

 divided. = Phlyctis. 



Sub-tribe VIII. Thelotremei. 



Apothecia verrucseform, open; spores 8, murali- divided. = 

 Thelotrema. 

 Apothecia urceolate ; spores murali-locular. = Urceolaria. 



Tribe XV. Lecideinei. 



Thallus crustaceous, squamose, scurfy, powdery, granulate, 

 areolate, continuous, rimulose, or evanescent ; spores 8 or numer- 

 ous, colourless or fuscous, simple or variously septate. =Lecide a. 



Thallus evanescent ; apothecia gymnotremoid, naked, black ; 

 spores 2-septate. = Odontotrema. 



Thallus evanescent ; apothecia lecideine, elevated, naked, black ; 

 spores numerous. = Schizoxylon. 



Tribe XVI. Grafhidei. 



Apothecia black, linear, parallel, plane, internally cinerascent ; 

 spores 8, simple. = Xylographa, 



