12 BRITISH LICHENS : 
85. Thelopsis Nyl. Thallus scarcely any visible, containing 
chrysogonidia: apothecia tuberculoso-spherical, with entire py- 
renium and numerous 3-septate spores ; spermogones not seen. 
86. Obryzum Wallr. Thallus none proper: apothecia on the 
thallus of Collemei, endocarpoid, with simple or septate corniculate 
spores ; spermogones unknown. 
~ 87. StrigulaFr. Thallus maculate, hypophlcodal, seldom effigu- 
rate, containing platygonidia: apothecia subinnate, with the 
pyrenium usually depressed, and with simple or 1-3-septate spores ; 
spermogones with thin straight spermatia. 
88. Melanotheca Fée. Thallus scarcely any: apothecia verru- 
carioid, numerous and confluent in the pyrenia, with septate 
spores; spermogones not observed. 
Series VII. PERIDIODEI Ny]. Thallus thin, often wanting: 
apothecia peridieine, without any ostiole. 
Tribe XXI. PERIDIEI Nyl. Thallus thin, maculate or none 
proper: apothecia forming a peridium. 
89. Thelocarpon Nyl. Thallus crustaceous, thin, verrucose, or 
rarely none: apothecia immersed in the thalline verruce, with 
numerous simple spores ; spermogones unknown. 
90. Endococcus Nyl. Thallus none proper: apothecia minute, 
globulose, with 1-septate spores; spermogones with thin straight 
spermatia. 
91. Mycoporum Flot. Thallus maculate or obsolete: apothecia 
rotundato-difform, containing many hymenia conjoined as in a 
common exciple, with variously septate spores; spermogones not 
observed. 
Family IV. MYRIANGIACEI Nyl. Thallus unstratified, 
entirely cellular; thalamium cellular, with superimposed theciferous 
cavities: fructification not discrete. 
92. Myriangium Mont. & Berk. ‘Thallus noduloso-pulvinate: 
apothecia sublecanorine, with irregularly septate spores; spermo- 
gones not seen. 
