:35. 



3G. 



;J7. 



3S. 



39. 



40. 



41. 



42. 



48. 



44. 



45. 



THE DETER^rrN.VTTOX OF LICUEXS T>f THE FIELD O 



Th. K+ yellow. Ap. witliout a tli. marg. 



Sp. brown. (Also the rare B. epic/cea.) ... Buellia canescens. 

 Usu. oil rocks. Th. closely ap[)ressed. A p. 



withath. marg Squamaria. 



On soil. Th. loss closely appress<f(lv Ap, 



orange-red or testaceous, without a th. 



niarg. but with a proper ])al<M- margin Lecidea testacea. 



Th. o£ small lobes or scpiamules (under 4 mm. 



broad) '^''• 



Th. of minute or indistinct lobes or s({ua- 



mules ; usu. much less than 1 mm, 



broad (o) ^^' 



Th. dark and gelatinous when moist. Algal 



cells blue-green (JVostoc) and scattered ... 5 (j)). 



Th. not gelatinous when moist. Algal cells 



forming a detinite layer and usu. green ... 38. 

 Th. with' small perithecia dotted about on 



the upper surface '*^- 



Perithecia absent. Tliecia (when present) 



with open disc (apothecia) ^^9- 



Th. bright bluish-green, Usu, on turf ...... Coriscmm. 



Th. not green, or if so, without the bright 



bluish appearance ^'^^' 



Th. usu. dark or with a bluish appearance. 



Alyal cells blue-green 41. 



Th. viu'iable but seldom dark. Algal cells 



green, though JVosfoc cells may be present 



in tubercles (cephalodia) 42, 



Algal cells Nosfoc. Ap. with thalline margin 



'(usu. crenulate). Sp. usu. simple Pannaria. 



Algal cells Nosfoc. Ap. without thalline 



margin. Sp. usu. simple Parmeliella. 



x^lo-al cells Scutonema. Ap. without th. 



marg. Sp. 1-septate Massalongia carnosa. 



Th. with cephalodia containing Nostoc. Ap. 



usu. sunk in the th Solorina. 



Th. without cephalodia. Ap. not sunk in 



thalline pits ■ 43. 



Th. yellow. K-f purple. Sp. 8, polarilocular _ 



and colourless .; ;•• Xanthoria. 



Th. of yellow iimbricatedlacinise, K — . Sp. 



many and colourless. (On trees. ) Candelaria concolor. 



Th. not yellow, or if so, K-. Sp. 8 not 



polarilocular • ■ • • 44. 



Th. of tbickish squamules without cortical 



cells or rbizinie beneath • • • . 4o. 



Th. of leaf-like lobes or lacinia? with cortical 



cells and rhizinse beneath, though these 



may be imperfectly developed and some- 

 times absent 47. 



Ap. without a thalline margin. Squamules 



scattered and often free from each other. . . Lecidea (Psora). 



