228 



MS 



[Ch. XI. 



to relieve the atmospliere of part of the carbonic acid which 



from 



earth. Mr 



formed 



regions of South America which are exceedingly damp to 

 the absence of species of plants peculiarly fitted for its pro- 

 duction. The abundance of coal, therefore, in certain dis- 



may have arisen from 



decompositio 



from a peculiarity in the atmosphere which enveloped the 

 globe in the Carboniferous period. In the Runn of Kutch 

 there is a great annual deposit of salt caused by the evaporation 



om ereoOTa 



unconnected with the chemical condition of the ocean, which 



more 



average proportion of chloride of sodium. 



The 



Kutch 



may 



the brine now held in solution by the ocean, but if so, future 

 geologists will have no right to conclude that during such an 



sodium 



more 



Nay 



& 



much 



forming, the waters of the ocean would contain less than 

 their average quantity of brine. 



Fossil shells and corals of the Coal Period. — If we now 

 turn from the flora to the fauna of the Carboniferous 

 period, we find among the invertebrate animals many large 

 chambered cells of Cephalopoda, as well as stone-lilies or 



encrinites, and corals, which bear 



affinity 



forms which flourished in those secondary periods, when, for 

 reasons already explained, a warm climate is supposed to have 

 prevailed. It may indeed be objected, in regard to the corals, 

 that they all belong to a type only met with in the primary 

 or paleozoic rocks ; that is to say, to the order Zoantharia 

 rugosa of Milne-Edwards, which 

 Permian era ; but these cup and star corals of the older or 

 quadripartite type have such a range, from tropical to 



became 



the 



northern regions 



that unless we believe the seas m 



low 



latitudes to have had a cool temperature, we must suppose 





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