THE FOSSIL RECORD 25 



mosses and Horsetails, with Gymnosperms and 

 primitive Seed-plants of classes now unknown, 

 characterise this famous Permo-carboniferous 

 Flora, the most important of all in the history of 

 the Vegetable World. 



The Carboniferous consists in England of 

 three main divisions: The Coal Measures, 

 the Millstone Grit, and the Carboniferous 

 Limestone. 



The Coal Measures, consisting largely of 

 the buried remains of vast swampy forests, 

 are the richest of all formations in fossil plants, 

 in all conditions of preservation. A peculiar 

 feature of certain English coal-beds (belonging 

 to the Lower Coal Measures of Lancashire and 

 Yorkshire) is the presence in the coal itself of 

 calcareous concretions called coal-balls, which 

 are packed full of petrified fragments of plants, 

 preserved with astonishing perfection. Coal- 

 balls also occur in the roof of the seams, and 

 contain a somewhat different Flora from that 

 of the seam itself. Similar coal-balls are known 

 to occur in the coal-fields of Germany and 

 Austria. 



In France, the Upper Coal Measures and Per- 

 mian are especially rich hi petrified specimens, 

 usually preserved in silica. 



Throughout the whole series, impressions and 

 casts of plants are abundant and of great 

 value in showing their external characters. 



