PREFACE. 



There is no branch of Palaeontology of so much importance to the Geologist, as the study of 

 Fossil Shells. In this opinion the Author is supported by tlu-ee of the greatest Living authorities. 

 Dr. Buckland says — " Concurrent with the rapid extension of our knowledge of the comparative 

 anatomy of extinct families of the ancient inhabitants of the earth, has been the attention paid 

 to Fossil Conchology ; a subject of vast importance in investigating the records of the changes 

 that have occurred upon the surface of the globe." Sir Charles Lyell remarks that " sheUs 

 are by far the most important class of organic beings which have left then* spoils in the 

 sub-aqueous deposits, and they have been truly said to be the Models which Natm-e has chiefly 

 selected to record the history of the former changes of the globe. There is scarcely any great 

 series of strata that does not contain some marine or fresh water shells." And again, Buckland 

 justly observes, in descantiag on the indispensable utiUty of the study of Fossils to a thorough 

 knowledge of Geology, that " to attempt an investigation of the structure and revolutions of the 

 earth, without appljong minute attention to the evidence afforded by organic remains, would be 

 no less absurd than to undertake to write the history of any ancient people, without reference 

 to the documents afforded by then- medals and inscriptions, then' monuments, and the ruins of 

 their cities and their temples. The study of Zoology and Botany has therefore become as indis- 

 pensable to the progress of Geology, as a knowledge of Mineralogy." And as Mantell truly 

 observes, " the shells of MoUusca, from then- durability, often escape obliteration under ckcum- 

 stances in which all traces of the higher orders of animals are lost, and they become, therefore, 

 of the utmost importance in the speculations of the geologist. In loose sandy strata, they often 

 occur in a high degree of perfection; in mud and clay, in a fragile state; in some instances, they 

 are silicified; and many limestones are wholly composed of shells, cemented together by calca- 

 reous spar." 



When the Author undertook the publication of the following work, it was Tvith a view of 

 supplying to Geologists a long-felt desideratum : namely, a work arranged either in systematic 

 or in stratigraphic order, embracing all the species known up to that time, and which might be 

 discovered dm-ing the progress of the publication. Mr. Sowerby's work, destitute of both these 

 advantages, had been discontinued for upwards of nine years, and there was no prospect of 

 its being resumed. 



