THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 123 



Another form is characterized by the medium sized, more or less 

 clustered and angulose apothecia, with coal-black, often glistening 

 disk; margin thin, not elevated, entire. 



Generally distributed over Europe and North America. 



3. BIATORELLA CLAVUS (DC.) Th. Fr. 



Patellaria clavus DC. Fl. Fr. 2 : 348. 1805. 

 Biatorella clavus Th. Fr. Lich. Scand. 2 : 409. 1874. 



Thallus wanting or represented by a few minute black specks 



Apothecia of medium to large size, at first concave, soon plane, 



circular, becoming irregular; disk black, hardly reddish black, not 



pruinose; margin thickish, erect, entire, becoming wrinkled; epithe- 



cium brown to black; hypothecium brown to brownish black; par- 



2 — 2.5 

 aphyses thread-like, thecium deep blue with I ; spores — M- 



Rare; on sandstone in the mountains. Widely distributed over 

 Europe and North America. 



XXVII. Acarospora Mass. 



Acarospora Massalongo, Ric. Sul. Aut. Lich. Crost. 27. 1852. 

 Acarospora A. Zahlbr., Ascolichenes, 152. 1907. 



Thallus crustaceous, of scales or warts, these scattered or crowded, 

 uniform or marginally lobed; apothecia innate or rarely sessile, 

 solitary or several in one scale, with a thalline margin, the disk 

 often narrow, circular or irregular; hypothecium clear or now and 

 then dusky, upon a layer of gonidia; spores minute, simple, broadly 

 eUipsoid to elongate. 



Rock and earth lichens distributed over the whole earth but 

 richest in species in arid or semi-arid regions; a considerable number 

 endemic to California. 



KEY TO SPECIES. 



A. Thallus yellow. 

 B. Thallus clear bright lemon-yellow with radiately lobate margin ; disk 



of apothecia yellow i. chlorophana 



BB. Thallus duller yellow, not radiate-lobate at margin; apothecia not 

 concolorous. 



C. Greenish yellow; disk reddish to dark red 2. bella 



CC. Sulfur-yellow; disk red-brown to red-black 3. schleicheri 



Proc. Wash. Acad. Sci., I^Iay, 1910. 



