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Genus 1 . Roccella. Disk of apoth. black, with a white bloom ; 

 spores 4 loc, colorless. Gonidia, according to Schwendener, of the 

 Sclerolicliens. An easily recognized genus of few species, of warm 

 regions, of which we have 4 spp. on the lower coast of California. 



Genus 2. Eamalina. Disk and thallus pale. Spores 2 loc, 

 colorless. A large genus, occurring throughout, but not abundant 

 in the Arctic region, of which we have about 16 spp. 



Genus 3. Cetraria. Disk colored differently from the thallus, 

 which is either fruticulose or dilated. (Spermatia usually marginal, 

 and the apothecia obliquely attached to the margin of the frond.) 

 Spores simple, colorless, small. A large, mostly northern and 

 western genus. 22 spp. 



- Genus 4. Evernia. Disk concave, colored differently from the 

 thallus. Spores simple, colorless, small. A small genus mostly 

 of temperate regions. 6 spp. 



" Genus 5. Usnea. Disk and thallus pale, the latter with a woody 

 core. Spores simple, colorless. A genus of few spp. occurring 

 throughout. 5 spp. U. barbata is cosmopolitan. 



Genus 6. Alectoria. Disk differently colored from the thallus, 

 which is cottony within. Spores either simple and colorless, or now 

 muriform and brown or decolorate. A mostly northern genus of 

 few spp. spp., one peculiar to the western coast, but which has 

 also been found in northern Europe. 



- Genus 7. Schizopelte. Apothecia terminal, flabelliform, the 

 disk colored differently from the th. Spores plurilocular, brown. A 

 singular plant, of which only one sp. is known, from California. 



Fam. 2. Parmeliei. Thallus horizontal, foliaceous, rarely as- 

 cendant ; beneath usually fibrillose. 



Genus 8. Speerschneidera. Spores 2-4= loc, colorless. Th. 

 orbicular depressed, fruticulose many cleft, cartilagineous-coria- 

 ceous. Fibrils deficient. A genus of a single sp. found in Texas 

 and Kansas. 



Genus 9. Theloschistes. Disk of apoth. yellow. Spores polar- 

 bilocular, or in one instance simply bilocular, colorless. Th. folia- 

 ceous, or reduced and squamulose, and now ascendant. A small 

 genus, occurring throughout. 3 spp. and 3 subspp. 



Genus 10. Parhelia. Spores simple, colorless, now large. Th. 

 imbricate-foliaceous, now ascendant, miostly fibrillose beneath. A 

 large, mostly northern genus. The th. is either glaucous, brown or 



