202 LICHENS. 



Lecidea (L. uliginosa, Plate XIV., fig. 7), a collection of 

 larger black apothecia on a thin grey crust. This 

 family numbers above sixty English members, varying in 

 colour to every shade of grey and green, and with brown, 

 yellow, grey, and black apothecia. They live indiscri- 

 minately on bark and stone. 



A small family called Urceolaria, forms extensive 

 patches of crust on rocks and walls, especially in lime- 

 stone districts. The Calcareous urceolaria is grey, with 

 grey chequered depressed lines, and small grey apothecia 

 (U. calcarea, Plate XIV., Jig. 8), we found it abundantly 

 in the Yorkshire dales. 



A very large family comes next in which there are 

 some important members. One, in particular (Lecan- 

 ora esculenta), presents the strange anomaly of a free 

 lichen, unattached to any habitat of wood or stone, 

 and drawing its entire subsistence from the air. The 

 Edible Lecanora is an Asiatic species, the apothecia 

 are found scattered on the ground, some as large as 

 a walnut, and are used in conjunction with wheat, 

 as food by the Tartars. In the English members of the 

 family the frond is still crust aceous, but increasingly 

 foliated at the margin ; the apothecia have generally 

 borders of a different colour to the disk, marking their 

 position as belonging to the Csenothalami, those lichens 

 whose apothecia is formed partly of the substance of the 

 thallus. There are groups of rocks in Swaledale which 

 afford first rate opportunities of studying the Lecanora 

 family. Recently taken into the enclosure surrounding 

 a country house, convenient paths now intersect the 

 wilderness ; and although there is still ample opportunity 



