BEITISH MOSSES. 51 



Lincolnshire is formed mainly of Hypnum fluitans. But 



FlO. 32. Magnified section of stem of Sphagnum cymbifolium. 

 s s 1 stem; s l x, mass of spirally threaded cells surrounding 

 stem. After Schimper. 



Sphagnum appears to be the main constituent of peat in 

 Ireland, Scotland, and, so far as my researches have gone, 

 in England ; the peculiar spiral threads of the cells of the 

 Sphagnum leaf being easily detected in the peat so long as 

 it retains traces of its organic origin. 



Ancient Forests. The Peat Mosses, and the sea-shores of 

 our islands and of the adjoining mainland, reveal, as is very 

 well known, traces of ancient forests. Manyparts of England, 

 nearly all the mainland of Scotland, the Hebrides, the Ork- 

 neys, and the Shetlands, Ireland, and Denmark, the shores 

 of both sides of the English Channel, Normandy, Brittany, 

 the Channel Islands, and Holland, and the shores of Norway, 

 all bear evidence to the presence of these primeval forests ; 



D 2 



