PEAT, LIGNITE, AND COAL. 69 
CHAPTER V. 
ON PEAT-WOOD, LIGNITE, AND COAL. 
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Lien. 3. NopuULE OF JRONSTONE INCLOSING A FERN-LEAF. 
Coalbrook Dale. 
Fig. 1.—The nodule in its natural state. 
2, 3.—The same, split open longitudinally. The leaf 
remains attached to fig. 2, and the impression 
of its upper surface is seen on fig. 3. 
4.—Outline of the form of the leaf, which is a species 
of Pecopteris. 
Berore entering upon the examination of the specific and 
generic characters of fossil plants, and the natural relations 
of the extinct forms with those of the existing Floras, it 
will be requisite to notice those vast beds of vegetable 
matter, in various states of carbonization, which occur in 
the palzozoic, secondary, and tertiary formations. 
