lyo HERRE 



XLIII. Lecanora Ach. 



Lecanora Ach. Lich. Univ. 77. 18 10. 



Thallus uniform crustaceous, becoming marginally lobed, or 

 squamulose and occasionally sub-foliaceous, or very rarely fruticose 

 and erect or decumbent; alga Protococcus. Apothecia permanently 

 innate in one section, or more often sessile, circular, with thalline 

 margin enclosing algae; proper margin little or not at all developed; 

 paraphyses unbranched, free; hypothecium clear or colored, not 

 black; spores nearly always 8, rarely 16 or 32, simple, colorless, ellip- 

 soid, ovoid, or globose, thin-walled, without halo. Spermatia thread- 

 like, straight, bowed, or sickle-shaped. 



A very large genus found all over the world and growing upon the 

 most diversified substrata. Many of the species exceedingly vari- 

 able and often difficult to determine, the varietal forms apparently 

 intergrading. 



KEY TO THE SPECIES. 



A . Thallus f ruticulose. 



/. Sect. Cladodium Tuck. Thallus f ruticulose to decumbent and 

 warty, without cortical layer; apothecia terminal or lateral. 



a. Thallus erect, short, effuse, not sorediate i. bolanderi 



aa. Thallus forming tufts or small mats; more or less sorediate 



2. phryganitis 

 A A . Thallus not f ruticulose. 



B. Thallus sub-foliaceous, marginally lobed. 



//. Sect. Placodmm (Hill.) Th. Fr. — Thallus sub-fohaceous, margin- 

 ally lobed, centrally passing from crustaceous forms to 

 squamulose; upper cortical layer well developed; apothecia 

 sessile. 

 b. Thallus very thick, tartareous; orange with CaChO,. 



3. pinguis 

 bb. Thallus thin, parmelioid, with long marginal lobes; no 



change with CaCkO., 4. saxicola 



BB. Thallus uniform crustaceous, not marginally lobate. 

 C. Apothecia sessile. 

 ///. Section Eulecanora Wainio. — Thallus uniform crustaceous, 

 areolate or warty; cortex present or more or less im- 

 perfectly developed; apothecia sessile. 

 c. On rocks. 



d. Apothecia black within '. 7. atra 



dd. Apothecia pale within. 



e. Thallus yellowish with CaCkO., 15. frustulosa 



ee. Thallus not affected by CaCl^02. 



