170 HERRE 



XLIII. Lecanora Ach. 



Lecanora Ach. Lich. Univ. 77. 1810. 



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 fruticulose. 



7. Sect. Cladodium Tuck. Thallus fruticulose 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 fruticulose. 



B. Thallus sub-foliaceous, marginally lobed. 

 II. Sect. Placodium (Hill.) Th. Fr. Thallus sub-foliaceous, margin- 

 ally lobed, centrally passing from crustaceous forms to 

 squamulose; upper cortical layer well developed; apothecia 

 sessile. 

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



3. pinguis 

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



change with CaCl 2 O 2 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 CaCl 2 O 2 15. frustulosa 



ee. Thallus not affected by CaCLA- 



