SECONDARY LIMESTONES. 243 



series. For these details and arrangements, which are 

 in reality partial and topographic, I must unavoidably 

 refer to themselves, and principally to Conybeare and 

 Phillips. 



Though beds, of the properly oolithic structure, 

 occur in the whole of this series, it also presents, in 

 colour, texture, and composition, examples of almost 

 every variety of limestone. To enumerate these, 

 would be a fruitless repetition ; and to give the details, 

 either of domestic or foreign examples, would exceed 

 the limits of a systematical work. The organic re- 

 mains are, equally, too numerous to be here quoted ; 

 while the mere enumeration would serve no purpose, 

 unless they were severally appropriated to the beds 

 which they are said to identify and discriminate, in 

 our own country at least. The book just referred to 

 will give what I need not reprint ; noticing only, that 

 with numerous genera of shells, they contain alcyonia, 

 corals, encrinites, crustaceous animals, fragments of 

 fishes and amphibia, together with many plants, and 

 conspicuous deposits of lignite coal. It is said to 

 have produced an Opossum in England ; which can 

 be no cause of surprise when it contains terrestrial 

 plants, amounting, it is said, to more than twenty, and 

 analogous to those of the coal series, since consisting 

 of palms, ferns, equiseturns, and lycopodiums. Yet 

 it ought surely to be obvious, that when remote beds 

 are said to be identified because their fossils are the 

 same, the proposition is identical and nugatory; since 

 it is simply to say, that similar fossils exist in two 

 places. The comparison of two shells, which all can 

 make, may prove those alike or different; but this is 

 conchology, not geology. 



The " Dolomite" of Jura, is said to appertain to 

 this division ; but this term having been applied to all 



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