THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 39 



KEY TO SPECIES. 



A. Thallus thin to very thin. 



B. Black, resembling a smear of black paint; on maritime rocks. 



5. melas 

 BB. Not black. 

 C. Very thin and powdery, or mostly obsolete; forming white spots 



on limestone 6. calciseda fusca-spora 



CC. Of minute ashen or gray granules; on sandstone. 



4. miiralis 

 AA. Thallus more or less areolate or scaly; from thin becoming thick. 

 D. Color pale. 



E. Areoles thick, bluish gray 7. stanfordi 



DD. Color dark to the naked eye. 



F. Thallus areolate or scaly, ashy gray under lens ; black appearance 



due to the numerous apothecia i . rupestris 



FF. Thallus some shade of brown. 

 G. Pale to dark olive brown, with a more or less greenish cast when 



wet 2. viridula 



GG. Dark brown to black, not becoming greenish when wet. 



3. nigrescens 



I. VERRUCARI A RUPESTRIS Schrader. 



Verrucaria rupestris Schrad. Spicil. Fl. Germ. 109. 1794. 

 Verrucaria rupestris Leighton, Brit. Angiocarp. Lich. 60. PL. 25. 

 f. 4. 1851. 



Thallus effuse, thin to thickish, apparently continuous, but really 

 minutely fissured and areolate or scaly; black to the naked eye, but 

 examination with the lens shows it to be ashy gray. 



The black color is due to the numerous, large, prominent, hemis- 

 pherical, and semi-immersed apothecia; perithecium thick, black, 

 dimidiate; amphithecium thin, pale brown; hymenial gelatine blue 

 with I; spores colorless to pale yellow, ellipsoid or sometimes pointed 



, 8i-ii 



at one end, ~ pL. 



20-25 



On rocks at Point Lobos, San Francisco, and elsewhere along the 

 ocean shore; probably occurring throughout our territory. Com- 

 monly distributed over the North Temperate region. 



I also doubtfully refer here a plant on sandstone, Castle Rock 

 Ridge, altitude 2000 feet, differing as follows: 



Thallus areolate, fissured, the areoles distinct or running into a 



