174 HERRE 



This very distinct lichen is abundant on rocks in the maritime 

 area; so far as the author is aware it is confined to the maritime belt 

 of central California. 



4. LECANORA SAXICOLA (Poll.) Ach. 



Lichen saxicola Pollich, Hist. Plant, in Palatin. Elect. 225. 1777. 



Lecanora saxicola Ach. Lich. Univ. 431. 1810. 



Lecanora muralis, Lecanora muralis a. saxicola, Lecanora muralis c. 



diffracta, and Lecanora muralis d. semitensis Tuckerman, Syn. N. 



Am. Lich. I: 184. 1882. 



Lichen diffractus Ach. Lich. Suec. Prodr. 63. 1798. 

 Lecanora semitensis Tuck. Proc. Amer. Phil. Soc. 



Thallus orbiculate, medium to large, closely appressed, of scales 

 or areolae centrally, becoming radiate at the circumference; the 

 lobes sinuate, plane or plicate, multifid, with crenate tips, parme- 

 lioid; color from glaucous green to pale yellow or brownish, the 

 squamules sometimes black-margined; KOH ; CaCW^ . 



Apothecia small to medium size, appressed, central, usually abun- 

 dant, sometimes obscuring the thallus; disk plane, becoming convex, 

 from pale yellowish passing into reddish brown; the pale margin from 

 entire becoming crenulate and flexuose, finally excluded; spores 



ellipsoid, 4 Q 9 ~ 7 V 



0-15 



Common on rocks throughout; occasional on fences and roofs of 

 houses. A variable lichen of world-wide distribution. 



var. DIFFRACTA (Ach.) 



The variety diffracta is distinguished by (a) its much darker thal- 

 lus, which passes finally into tawny yellow, brick-red, or brown; (b) 

 the scales become reduced to separate, distinct areoles which are 

 usually black-margined; (c) the much narrower and shorter marginal 

 lobes. Apothecia infrequent; small to very large, and from plane 

 and circular becoming difform or highly flexuous; from pale flesh- 

 color passing to dark reddish; the light colored denticulate margin 

 flexuous or sometimes excluded. 



Abundant and variable on sandstone at 2000 feet and above; 

 through the coalescence of adjacent plants of ten covering large areas. 



