60 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. I. 



descent lava, while trees placed in circumstances unfavourable 

 to their petrifaction were consumed : but the latter, being 

 either saturated with water, or fresh and green, were con- 

 sumed slowly, and left cylindrical moulds in the cooled 

 basaltic scoriae, with impressions of the external surface of the 

 bark ; and these moulds being filled up by a subsequent 

 eruption, formed casts of the consumed trees in basalt. 1 



With this notice of the petrified forests of Portland and of 

 Australia, our survey of the collection of fossil vegetables 

 contained in the British Museum is brought to a close ; for 

 the objects that remain to be noticed in this room belong to 

 a very different subject. Desultory and somewhat uncon- 

 nected as the descriptions and illustrations have neces- 

 sarily been, I would fain hope that this imperfect attempt to 

 invest with a higher interest these relics of the extinct tribes 

 of vegetables that flourished in the earlier ages of the earth's 

 physical history, will not prove unsuccessful. 



1 " Physical Description of New South Wales," by Count Strzelecki. 



