306 



POPULAR HISTORY OF LICHENS. 



Tffl Inner tunic pale. 



8. Verrucaria mutabilis [mutabilis, changeable). Thal- 

 lus umber-coloured. Apothecia minute, scattered, nume- 

 rous^ round, sometimes shining. Spores oblong, pale, small. 

 (E. B. 1712.) 



Sometimes forms orbicular, or dendritic-effigurate patches 

 on stones in shady places. 



§§§ Perithecium spreading at base. 

 % Inner tunic black. 



9. Verrucaria maura (Maums, a Moor). Thallus thick, 

 dark reddish-black, coarsely cracked, smooth, shining, papil- 

 lose, effuse. Apothecia scattered, largish, hemispherical, 

 wholly immersed, thalline papillae which cover them marked 

 by a large, distinct pore. Spores oblong, double-walled, 

 pale. (E. B. 2456.) 



Common on rocks and cliffs on various parts of the 

 east coast of Scotland, as about Dunbar. 



^f^T Inner tunic pale. 



10. Yerrucaria margacea. Thallus greyish-brown or 

 greenish, contiguous or slightly rimulose, forming orbicular, 

 determinate maculae, or effuse. Apothecia partially project- 

 ing from small, conical, thalline papillae ; expanded base of 

 perithecium visible through the thin thallus (this base re- 



