10 



in some of the tropical regions. On these nodules being 

 broken, the preserved remains are generally discovered on 

 each of the broken sides of the nodule ; not, as might be 

 expected, displaying different sides of the vegetable, but 

 the same side of the leaf, for instance, on each broken 

 surface ; in one, in alto — in the other, in basso relievo. The 

 explanation of this curious circumstance, which long puzzled 

 the oryctologists, is found in the vegetable matter, during 

 its passing through the bituminous change, having become 

 softened, and having filled its own mould with its melted 

 and subsequently hardened substance ; the nodule, on being 

 broken, showing on one side the surface of the adherent 

 bituminous cast, and, on the other, the corresponding mould. 

 In the argillaceous and bituminous slate forming the 

 floors and roofs of coal mines are vast collections of the 

 black bituminized remains of gramina, junci, cryptogami, 

 and of numerous other plants, agreeing in their general 

 characters with those of succulent plants, but differing 

 from the recent ones known in Europe by their vast mag- 

 nitude, and by the richness of the ornamental markings 

 which appear on their trunks. 



Description cannot succeed in an attempt to give an 

 idea of the beauty and varieties of the figures which are dis- 

 played on the surface of many of those fossils ; and which 

 have been supposed to owe their markings to the bark of 

 different trees of supposed antediluvian existence. Some 

 are ornamented by regularly disposed straight plain ribs, 

 arranged longitudinally or transversely over their whole 

 surface ; some by the decussation of nearly straight lines 

 obliquely disposed ; and many, by the alternate contact and 

 receding of gently waving lines, forming areas regularly, 

 but most singularly varying in their forms, and having in 

 their centres tubercles and depressions from which spines, 

 or setae, have in all probability proceeded. In others, lines 

 obliquely disposed intersect each other at angles, varying 



