VI ADDRESS. 



Owen, Gray, Broderip, Sowerby, &c, and have been thus 

 enabled to embody much new and important matter commu- 

 nicated from time to time by these authors, but hitherto com- 

 paratively lost in various scattered memoirs and monographs. 



The whole of the descriptive characters of the several divi- 

 sions have been carefully revised, and such as have seemed 

 sufficiently appropriate are adopted ; still, in this part of the 

 work, the alterations are not inconsiderable. 



The historical and scientific observations have been arranged 

 with care, and are detailed in as concise a form as possible. 

 The genera are furnished with so many examples of species, 

 with their synonyms, as have been considered of interest, and 

 each is accompanied with one or more accurate figures. 



The illustrations have been kindly contributed by the Messrs. 

 Sowerby ; two hundred plates are selected from the " Genera 

 of Shells," fifty from the " Conchological Illustrations," and 

 fifty are entirely new and original. 



In conclusion, I beg to return my sincere thanks to the 

 Rev. Mr. Stainforth, for the kind manner in which he has 

 devoted a considerable portion of time to the perusal of my 

 manuscript, and have now only to hope, that a long and 

 exclusive study of the Lepades and Conchiferous Mollusca 

 will be rewarded by the attention of naturalists. 



L. R. 



73 York Road, London, 

 September 7th, 1841. 



