The scientific Reader will feel that much value has been added to the 

 ])reserit work, from tlie whole of the Palaeontology, during its progress 

 tiirough the Press, having had the great advantage of passing under the re- 

 vision of Mr. Broderip, and from tlie botanical part having been submitted 

 to Mr. Robert Brown. I have also to acknowledge my obligations to Mr. 

 Clift for his important assistance in the anatomy of the Megatherium; to Pro- 

 fessor Agassiz of Neuchatel for his unreserved communications of his disco- 

 veries relating to Fossil Fishes; to Mr. Owen for his revision of some parts 

 of my Chapter on Mollusks; and to Mr, James Sowerby for his assistance in 

 engraving most of my figures of radiated animals, and some of those of Mol- 

 lusks. 



To all these Gentlemen I feel it my duty thus to offer my public ac- 

 knowledgements. 



Many obligations to other scientific friends arc also acknowledged in the 

 course of the work. 



The Wood-cuts have been executed by Mr. Fisher and Mr. Byfield, and 

 most of the Steel plates of Mollusks by Mr. Zeltter 



