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POPULAR HISTORY OF LICHENS. 



Lichens" or " Shield-edge Lichens," in allusion to the ap- 

 pearance or resemblances of their thallus or apothecia. 



Nat. Ord. VII. LECANOREACEj®. 



Fam. Char. Thallus crustaceous, effigurate or uniform. Apo- 

 thecium scutellate, sessile, superficial : thalamium concave or 

 flattish, frequently becoming tumid, varying in colour. 



Genus I. LECANOBA, Ach. 



Gen. Char. Thalamium always naked, normally immarginate, 

 flat or tumid. (Name from XtKavrj, a dish or platter, in allusion 

 to the form of the apothecium.) 



* Thallus squamulose ; central squamules crowded into an 

 areolate crust. 



1. Lecanora crassa (crassus, thick or fertile). Thallus 

 greenish-grey, usually white-pruinose, — below black, white 

 at circumference ; peripheral squamules subradiose-plicate, 

 incised-lobate, rounded and crenate. Apothecium appressed, 

 brick-coloured; margin tumid, at length evanescent. (E. B. 

 1893, var. ctespitosa.) 



There are several varieties, depending on the form and 

 arrangement of the central and peripheral squamules, the 



