250 



POPULAR HISTORY OF LICHENS, 



Genus II. GBAPHIS, Ach. 



Gen. Char. Apothecia lirellate, immersed. Perithecium carbo- 

 naceous, covering only sides and not base of thalamium, which is 

 canaliculate, having a proper margin and an accessory thalline 

 margin. Thallus crustaceous or membranaceous. (Name from 

 ypacj>Ls, a design or sketch.) 



1. Graphis scripta (scriptuSy written). Thallus thin, 

 membranaceous, continuous, even; lirellse emergent, slen- 

 der, contracted here and there, extremities acuminate ; pro- 

 per margin thin, elevated, wavy, and crisped ; thalline mar- 

 gin membranaceous. Thalamium rimseform, naked. Spores 

 oblong or oval, margined, each containing eight to ten hori- 

 zontal rows of subrotund, margined, yellow cellules. 



A common species, growing on the smooth barks of vari- 

 ous forest and roadside trees, as the oak, ash, elm, birch, and 

 hazel. The two following species are also common in simi- 

 lar habitats, and closely resemble it in general characters. 



2. Graphis pulverulenta has a subtartareous, rugulose 

 thallus. Lirellse subsessile, broadish, extremities cuspidate ; 

 proper margin thick, uniform ; thalline margin elevated, tu- 

 mid : thalamium broadly canaliculate, pruinose. (E. B. 

 1754.) 



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