GENERA AND SPECIES. 103 



t 



lower genera here included present widely different 

 spore-chanicters, which would perhaps indicate a re- 

 moter relationship than is assumed. In some instances 

 the thallus is very rudimentary. Because of the ab- 

 sence of well-marked family-characters, the amateur 

 is likely to confuse some of the lower genera with the 

 lower genera of the ParmeliacecB, and perhaps some 

 Verrucariacece, to be considered later. 



KEY TO THE GENERA. 

 Thallus indistinctly crustose to Avarty. 

 Spore-sacs bearing sixteen simple colorless spores, 



o , . . , 1- Biatorella. 

 Spore-sacs bearing eight spores (usual number). 

 Hypothecium and spores colorless. 

 Spores elliptical. 



Two-celled ^. Biatorina. 



^^'"P^e s. Biatora. 



Four-celled ^. BiUmbia. 



bpores acicular, six to eight-celled . .5. Bacidia. 

 Hypothecium dark. 

 Spores colorless. 



Simple 6. Lecidea. 



Two-celled 7. CatiUaria. 



Four-eel ed g. Cdidiopsis. 



Spores dark. 



Two-celled 5. BnelUa. 



Four-celled , jO. Buellopsis. 



bpore-sacs bearing from one to six spores, hypothecium 

 colorless or yellowish. 



Spores simple, colorless, large . . 11. Megahspora. 

 Spores multilocular.i 



^^^^: 1^. Lopadium. 



rry. 11 F?-'"''''''' ^3- Gyalecta. 



Thallus fohose, entire. 



Small, adnate to substratum, spores simple, colorless, 

 T , .,. ^4- Psora. 



-Large, umbilicate ; apothecia black, sessile. 



Spores simple, colorless 15. Gf/rophora. 



Spores multilocular, large .... 16. Umbilicaria. 



-^.^^/''""l'-'*'*'"'^'".''^"*'^^" '» nieant many celled spores havine 

 ■epta formed m two plants of thespore. i^v.icb imviug 



