32 



straw-colored. 19 spp., 10 subspp. What seems to be P. mollius- 

 cula fertile, was collected by Mr. Brandegee in the Rocky Moun- 

 tains. 



Genus 11. Physcia. Spores 2, rarely 4 locular, brown. Th. 

 foliaceous, ramose-laciniate, or now ascendant, mostly flbrillose. A 

 rather large genus, throughout. 10 spp. and 10 subspp. 



Genus 12. Pyxine. Hypothecium black, and in one section 

 the exciple blackening. Spores 2, rarely 4 loc, brown. Th. ad- 

 nate, semi-crustaceous and now foliaceous. A small genus of the 

 Atlantic coast north and south. 2 spp. and 2 subspp. 



Fam. 3. Umbilicakiei. Thallus horizontal, foliaceous, submo- 

 nophyllous, coriaceous, dark-coloved, more or less flbrillose, at- 

 tached to the substrate by a single point. 



Genus 13. Umbilicaria. Apoth. subscutellseform, variously 

 difform, black, without gonidia, mostly at length lirellseform-proli- 

 f erous. Spores from simple at length granulose, or more rarely mu- 

 riform, becoming brown. A large genus of Arctic, Alpine and 

 temperate regions, growing upon rocks. 17 spp. 



Genus 14. Omphalodium. Apoth. much as in Parmelia. Spores 

 simple, colorless. A small genus, of which one sp. has been found 

 in Arizona. The other spp. occur in South America and Africa. 



Fam. 4. Peltigeeei. Thallus piano-ascendant, foliaceous, more 

 or less villous beneath, and veiny, and now cyphellate. Gonimous 

 stratum of either gonidia or gonlmia. 



Genus 15. Sticta. Apoth. submarginal, elevated, now black- 

 ening. Spores fusiform-acicular, 2-4-plurilocular, fuscescent or 

 colorless. Th. foliaceous, wide lobed, rounded or elongated, be- 

 neath villous and cyphellate or now marked with bare spots. Go- 

 nimous stratum of both kinds. A large genus of temperate and 

 tropical regions, in the former often sterile. 17 spp. and 2 subpp. 



Genus 16. Nephroma. Apoth. reniform, innate on the under 

 sides of the lobules of the circumference. Spores subfusiform, 4 

 loc, fuscescent. Thallus frondose, more or less villous beneath, 

 not veiny. Gonimous stratum of both kinds. A small genus of 

 temperate regions. 6 spp. 



Genus 17. Pettigera. Apoth. peltseform, adnate to the upper 

 side of the extended lobes. Spores fusiform or acicular, 4-pluri- 

 locular, at length colorless. Thallus veiny and villous beneath, 



