72 THE AMERICAN MONTHLY [Mar., 



E 



Spores polar bi-locular. 



1 Apothecia scutellaeform, tliallus yellowish foliaceous, the disk 



yellowish orauge. 9 Thelosehistes 



1 Apothecia zeorine or biatorine, thallus fruticulose, uniform and 



often yellowish 30 Placodium 



F 



Spores fusiform. 



1 Spores brown a 



a Apothecia orbicular, innate 18 Solorina 



a Apo. lirellaelorm 51 Opegrapha 



a Apo. rounded or oblong 56 Arthonia 

 1 Spores fucescent b 



b Apo. scutellaeform 14 Sticta 



b Apo. reniform 15 Nephroma 

 1 Spores colorless c 



c Th. pendulous ; disk of apothecium black, with a white 



bloom 1 Eoccella 



c Th. granulose 27 Collema 



c Th. of jointed filaments 42 Coeogonium 



c Th. Iruticulose 1 



1 Apo. disk black with a white bloom 1 Eoccella 



1 Apo. zeorine 31 Lecanora 



1 Thallus of jointed filaments 42 Coeogonium 



1 Apothecia patellaeform X 



X With podecia 39 Stereocaulon 



X Without podecia 46 Lecidea 



1 Thallus caulescent 46 Lecidea 



1 Apothecia scutellaeform y 



y Thallus mostly dark green 27 Collema 



y Th. mostly lead color 28 Leptogium 

 c Th. froudose 2 



2 The underside with cyphels 14 Sticta 



2 Villous and veiny beneath 16 Peltigera 

 c Thallus foliaceous 3 



3 Coriaceous cartilagenous, the underside with cyphels 14 Sticta 

 3 Dark green 27 Collema 



3 Lead colored z 



z Cortical layer, parenchymatous spores ovoid- ellipsoid 



28 Leptogium 

 z Cortical layer distinct, spores fusiform quadri-locular 



29 Hydrothyria 

 c Thallus lobulate 4 



4 Apothecia zeorine 31 Lecanora 



4 Apo. patellaeform p 



p Apothecia stipitate 43 Baeomyces 

 p Apo. sessile q 



q Exciple paler than the disk 44 Biatora 



q Exciple coal black 46 Lecidea 

 c Thallus obscure or almost obsolete 5 



5 Apothecia lirellseform 51 Opegrapha 

 5 Apo. rounded or oblong 56 Arthonia 

 5 Apo. iEuate, superficial 68 Sagedia 



c Thallus uniform 6 



