448 THALLOPHYTES 



first punctiform-impressed, always open, often horny, and placed 

 upon a carbonaceous stratum. Thallus horizontal, arising from a 

 hypothallus, somewhat crustaceous, effigurate, or uniform. 



SECTION 1, Thallus effuse, uniform. 



SUBSECTION 1. AREOLATAE. 



Crust innate, originally areolate or becoming so ; hypotltallus black. 

 * SAXICOLAE. 



1. Jit. albo-eaerillescens, Fr. [White-bluish']: Crust at 

 first continuous, bluish becoming whitish ; apothecia produced from 

 the crust ; margin of the annular exciple thin ; disk waxy, black, 

 caerulescent-pruinose, white within. 



Far. b. immersa, Fr. crust very than and whitish, or wanting; apothecia small, 

 often immersed. 

 Hob. On rocks, and stones : Far. b. on limestone. 



2. L.. lapicida, Ach. [Stone-cutting'] : Crust at length areo- 

 late-verrucose, from glaucous becoming cinereous-white; apothecia 

 superficial, produced from the cortical layer, sessile, not pruinose, 

 horny and cinerascent-black within, with an even naked disk, and 

 a thin, at length flexuose margin (or, the margin disappearing, 

 finally confluent and irregular). 



Sab. On rocks and stones. 



3. It. atro-alba, Ach. [Mack and white"] : Crust somewhat 

 areolate (the areolae commonly discrete, verrucaeform), opaque, 

 fuscous and greyish-white ; apothecia produced from the hypothallus, 

 (small,) the obtuse margin scarcely discrete from the naked, at 

 length somewhat umbonate, disk. 



Sab. On rocks, and stones. 



* * CORTICICOLAE. 



4. li. parasfcma, Fr. [Counterfeit*]: Crust somewhat leprous, 

 glaucescent, becoming verrucose-areolate, limited by the black 

 hypothallus; apothecia sessile, opaque; exciple cupular, with a 

 thin margin ; disk horny, naked, very black. 



Sab. On trunks, and dead wood: very common. 



5. JL. enteroleftca, Fr. [Internally white} ; Crust at first 

 continuous, glaucescent, deliquescing, limited by the black hypo- 

 thallus ; apothecia adnate ; exciple annular, with a thin margin ; 

 disk somewhat wavy, often hyaline, or caerulescent, whitish within. 

 Sab. On smooth trunks. 



TRIBE 3. GRAPHIDA V CEAE. 



Apothecia of various form ; an altered thalline carbonaceous proper exciple, or an 

 originally proper exciple margining a gyrose and proliferous-papillate, or canalicu- 

 late disk. 



603. UMBIL,ICA;RIA, . 



[So named from the umbilicated Thallus.] 



Apothecia superficial, the closed thalline exciple becoming a carbon- 

 aceous proper exciple, more or less open, and of various form ; 

 disk horny, ascigerous, finally chinky, or gyrose-plicate, with an 

 incurved margin. Thallus horizontal, cartilagineous, foliaceous, 

 eubmonophyllous, afiixed by a central point. 



