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merates less developed. We find, at the same time, new divisions 

 of the dolomites ; some of which abound in organic remains, having 

 a resemblance to the fossils of the carboniferous strata, and being 

 in a few instances specifically the same with them. We also find 

 among them many new species of organized beings. Still the 

 sequence is incomplete ; the fossils of the dolomitic beds make but 

 little approach to the fossils of the lias : and no part of the British 

 Isles has hitherto supplied us with the intervening terms of the series. 

 But if we extend our inquiries to the secondary formations of Ger- 

 many and France (particularly in the regions of the Vosges, or on 

 the banks of the Neckar), we meet with a solution of our difficulties. 

 In the place of our barren deposits, between the magnesian lime- 

 stone and the lias, we have three great formations, each charac- 

 terized by its suite of fossils ; and among them we find a series of 

 zoophytes, and shells, and great reptiles, gradually leading us to 

 the organic types of the lias and the oolites. In proof of what I am 

 stating, I need only refer you to that part of our collection, which 

 we owe to the liberality of M. Voltz, whose labours have thrown 

 so great a light upon this interesting chapter of the physical history 

 of the earth. 



In this way, by successive but secure inductions, we resolve our 

 first difficulty; and are no longer startled at the change of organic 

 types, in the west of England, between the coal measures and the 

 lias. For between the times of their deposition, there were com- 

 pleted at least five great geological periods; each distinguished 

 by its own group of animals, and each, therefore, probably con- 

 tinued during a long succession of ages. I must, however, for- 

 bear : the subject is boundless ; but our time allows not of further 

 details. 



It is, I think, a matter of regret that there have not appeared, from 

 time to time, in our language, works placing clearly before the world 

 the progress of geology, the laws of its induction, and the subjects of 

 its speculations. Such works, however, demand more than common 

 powers, — a grasp of details only acquired by practical experience ; 

 and habits of mind fitted for the exhibition of them, in their most 

 simple and general form. But above all, they require a moral ele- 

 vation, and a dignified forbearance, to free the mind from those at- 

 tractive visions of ancient cosmogony, and those seductions of fanciful 

 hypotheses, by which the history of geology has so often been de- 

 graded. 



It is indeed true that an essay representing our science as it now 

 is, must in a few years be left at a distance by the progress of new 

 discoveries. At the same time, to no works in the history of physics- 

 do we revert with more pleasure and instruction, than to those 

 which record the progress of discovery, and the early approxima- 

 tions to general truth. Their lessons of wisdom remain ; and we 

 look back to them with veneration, as to ancient monuments, which, 

 however rude, or ill suited to the fashion of our day, still bear the 

 stamp of the genius that produced them. 



