KEY TO THE ARRANGEMENT. 



Ser, L GYMNOCAEPI (Schrad.) Fr. 



Apothecia normally open- either shield-like (scutellaform) 

 or dish-fee (patellceform) or difform, becoming elongated 

 (lirellceform} or goblet-shaped and the disk compacted of 

 naked spores (crater if orm). 



Trib, 1, PARMELIACEI, Apothecia rounded, margined by 

 a thalline exciple (scutellseform), which includes also 

 now, more or less distinctly, a proper exciple, when the 

 fruit is called zeorine. 



Fam. 1. USNEEI. Thallus sub-vertical and fruticulose, or 

 pendulous ; more rarely depressed, and dilated (foliace- 

 ous). 



1. ROCCELLA. Disk of apothecium black, with a white 



bloom. Spores fusiform-oblong, 4-locular, colourless. 

 Thallus fruticulose, or pendulous ; somewhat leathery. 



2. RAMALINA. Disk and thallus pale. Spores ellipsoid 



and oblong, 2-locular, colourless. Thallus fruticulose, 

 or pendulous; compressed or subfoliaceous, cartila- 

 gineous. 



3. CETRARIA. Disk coloured differently from the thallus, 



to the tips or margins of which the apothecia are 

 attached. Spores sub-ellipsoid, simple, colourless. 

 Thallus either fruticulose, or depressed and dilated 

 (parmelia3form) more or less cartilagineous. 



4. EVERNIA. Disk concave, coloured differently from the 



thallus; the apothecia at length often cyathiform. 

 Spores sub- ellipsoid, simple, colourless. Thallus fru- 



