THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 107 



ovoid or broadly ellipsoid, - - /*; according to Tuckerman, 



20 25 

 solitary, in twos or in fours, _ / 



O 



On igneous rocks and sandstone throughout, but most abundant 

 on the higher peaks. Often intermingled with Lecidea scotopholis 

 Tuck., which is very similar in appearance. 



Type locality, sandstone rocks in the Oakland Hills. Reported 

 from a number of stations in California, Oregon, and Washington, 

 and probably occurring everywhere west of the Sierras. 



5. RHIZOCARPON GEMINATUM (Ft.) Korb. 



Lecidea geminatum Flotow, in litt. 



Rhizocarpon geminatum Korber, Syst. Lich. Germ. 259. 1855. 



Buellia petrcea c. montagnaei Tuck. Syn. N. Am. Lich. II: 102. 



1888, in part. 



Thallus of scattered or loosely approximate, thin, round, flat squam- 

 ules, dark gray and blackening; hypothallus indistinct. 



Apothecia small, circular, sessile; disk flat, black; margin slightly 

 turgid and elevated, entire and persistent, black; epithecium granu- 

 lose, violaceous black; hypothecium blackish brown; paraphyses 

 coherent; hymenium pallid; asci inflated saccate; spores in twos, 

 either colorless or dark smoky gray, from 4 locular becoming muri- 

 16 20 



On rocks in Hidden Villa Canon and elsewhere in the mountains 

 and foothills, at elevations of a few hundred feet. A common Euro- 

 pean lichen, which is probably also widely distributed in North 

 America. 



6. RHIZOCARPON PETILEUM (Flow.) A. Zahlbr. 



Lecidea petrcea Flotow, in litt. 



Rhizocarpon petraum A. Zahlbr. Ascolichenes, 138. 1907. 



Buellia petraa Tuck. Syn. N. Am. Lich. II: 101. 1888. 



Thallus usually small, orbiculate to effuse, thin, uniform, and 

 minutely rimose, or becoming thickish an 1 sub-tartareous, more or 

 less roughened and minutely verrucose; upon a black, occasionally 



Proc. Wash. Acad. Sci., May, 1910. 



