NOVEMBEE. 527 



some of our finest foliaceous lichens. The sulphur 

 Parmelia (P. caperata) grows very large, and is a con- 

 spicuous object on orchard trees, while P. saxatilis 

 grows every where on trees, stones, rocks, and walls. 

 P. ompJialodes is also very abundant on rocks in 

 exposed situations, especially in the vicinity of the 

 sea, where it wholly covers extensive surfaces with its 

 deep purple thalli. 



The vicinity of old ocean is very favourable to 

 lichenic growth, for the humid fogs for ever arising 

 from its surface even in summer, and sleeping among 

 the twilight woody glens through which alpine rivulets 

 steal to the roaring monarch's embrace, nourish the 

 species that in more inland situations would vainly 

 struggle for extension amidst the continued burning 

 heats of summer. Thus it has occurred to me to 

 find more luxuriant specimens of Lichens on the rocks 

 about Yarmouth, North Wales, than I any where 

 else remember to have seen. Here the beautiful 

 Parmelia Icevigata covers the massy stones on the 

 margin of the beach, profusely covered with large 

 bright chesnut fructification ; P. perlata spreads to 

 a great size upon the rocks above, accompanied by the 

 pitchy-brown thallus of P. Fahlunensis, and the closely 

 adnate lobes of the tanned sun-burnt Parmelia (P. 

 aquila.) In the groves about Tan-y-bwlcJi, I also no- 

 ticed that the trees were profusely adorned with the 

 very beautiful orbicular Green Parmelia (P.lierbaced), 

 in exuberant fructification. Limestone rocks often 

 display species almost peculiar to that kind of stone 

 as the tiled Sq_uamaria crassa, and the leathery Endo- 

 carpon miniatum, so abundant on the rugged carboni- 

 ferous limestone of the romantic cliffs of Cheddar, 



