102 CRYPTOGAMIA LICHENES. 



CONNOT found in the 100 parts, 18 parts of lime, combined 

 with 29.4 of oxalic acid. Nearly the same quantity of 

 oxalate of lime was found in Porina pertusa, Isidium coral- 

 linum, Lecanora tartarea, and some others which do not 

 occur in this neighbourhood. u The oxalate of lime bears 

 the same relation to the Cryptogamia as carbonate of lime 

 to corals, and phosphate of lime to the bony structure of 

 the more perfect animals. The oxalate of lime diminishes 

 gradually in the family of lichens, in proportion as the 

 species lose their granular crustaceous texture, and ap- 

 proach more and more to the membranous or cartilaginous, 

 although these latter also contain a considerable quantity 

 of this salt. From the vast abundance of these lichens, it 

 is evident that they may afford a means of obtaining oxalic 

 acid in great quantity, and at a cheap rate." Edin. Phil. 

 Journ. xiii. 194. 



62. VERRUCARIA. 



1. V. epigea> crust yellowish-green, thin, granular when dry ; 

 apothecia small, tubercle-like, dull black, with a central lighter 

 coloured nucleus. ACHAR. Synop. 96. Liclien terrestris, Eng. Sot. 

 t. 1681. 



Hab. Dry barren banks, near Berwick, rare. 



ACHARITJS says the tubercles are black internally, but in our 

 specimen the nucleus is rather buff coloured. When wet, 

 the crust is soft and somewhat slimy. 



2. V. epidermidis, " crust exceedingly thin, spreading, quite 

 white; fructification minute, roundish, sub-elliptical, tubercles 

 semi-immersed, the interior white." GREV. Fl. Edin. 353. 



Hab< On the bark of the birch, rather rare. 



63. PORINA. 



1. P. pertusa, crust bluish-grey, even, thin, spreading, tuber- 

 cular or warted, the warts perforated or marked with depressed 

 black points, internally cellular, whitish.. HOCXK. Scot. ii. 45. 

 Lichen pertusus, LIGHT F. Scot. 802. WITH. iv. 16. Sphceria per- 

 tusa, BOLT. Fung. t. 126. DILL. Muse. t. xviii. f. 9. 



Hab. Trunks of trees, most common on ash. 



