INTRODUCTION* 
5 
Ferns abound in a fossil state in the coal-measures; 
magnificent trees belonging to this family, or closely 
allied to it, are found continually in our coal-pits, and 
many a rude block of coal or ironstone is adorned by 
delicate tracery stamped upon it incalculable ages past 
by the feathery frond of a delicate fern. Ninety-eight 
different species have been determined among coal- 
fossils, twenty-one have been found in oolite rocks, 
seven in the triassic strata, and one in the chalk. 
