COAL. 311 



tables resembling equisetums, accompanied by others 

 analogous to ferns and lycopodiums, and, as it is 

 thought, to palms ; with some which appear to pos- 

 sess no exact living analogies. The fluted and the 

 scaly stems and trunks, distinguished by the terms 

 Lepidodendron and Syringodendron, are the most re- 

 markable, as they are the most obscure. The genera 

 seem to be very limited, as far as they can be deter- 

 mined from such imperfect specimens ; but it is ima:- 

 gined that the species exceed three hundred, or ap- 

 proach to four. How far they may be considered as 

 tropical plants, I have already had occasion to en- 

 quire ; while, when it is said that at this period of the 

 earth no dicotyledonous plants existed, and that the 

 chjef vegetable creation was a cryptogamous one, we 

 cannot but be surprised at the minute progress which 

 philosophy has hitherto made among the cultivators 

 of this science. The Geologists of a future world, 

 whose researches may begin and end in a rock formed 

 out of the Sheppey clay, will perchance determine, 

 under similar reasoning powers, that the world pro- 

 duced no plants but hazels. 



In the sandstones, the most frequent vegetable ap- 

 pearance is that of concretions of sand bearing the 

 impression of the trunks just noticed ; and, in these 

 cases, while the woody matter of the tree has disap- 

 peared, the bark is sometimes converted into coal. 

 These are often compressed, as if by the superincum- 

 bent weight, and are also recumbent ; but, there have 

 also been found remains of trees similarly changed, in 

 an erect position, with the branches attached. 



Such are the organic appearances connected with 

 coal ; all of them bespeaking a terrestrial, not a sub- 

 marine origin, for the general series in which it is 

 found. Their aquatic nature equally indicate! the 



