INTEODUCTIOK 



The special Collection which is made the suhjeet of this compilation 

 consists of over 39,000 shells obtained from the Oligoccnc and Eocene 

 strata of the more important localities situated in the London and Hamp- 

 shire Basins. 



The class Lamellibranchiata comprises 11,516 specimens, represented 

 by 648 species and varic'ties, of which 428 arc described, the remainder, 

 220, being undcscribed or bearing manuscript names only. The Gas- 

 teropoda contain 27,421 specimens, consisting of 1151 species and 

 varieties, of which 786 aie described and 365 undcscribed. Lastly, the 

 Cephalopoda number 254 specimens, containing 15 described species. 

 These items yield a total number of specimens of 39,191, representing 

 1229 described and 585 undcscribed (or manuscript) names. It is the 

 author's intention to describe and figure in due course all those specimens 

 bearing manuscript names ; but as a preliminary measure it was deemed 

 advisable to retain them in this work, as so many have found their way 

 into published lists, especially in foreign collections ; and although they 

 can take no rank at present in the recognized specific nomenclature of 

 Conchology, they arc of considerable interest in the study of the facts 

 connected with generic distribution. 



The classification of the genera and families has been mainly drawn up 

 from that proposed by the late Dr. Ferd. Stoliczka in his monogra])h8 on 

 the " Pelecypoda " and "Gastropoda," both published in the Memoirs of 

 the Geological Survey of India (vide Bibliograph}'), with such additions 

 and emendations as have been subsequently made by Dr. Paul Fischer 

 and other eminent systcmatists. The merits of Stoliczka's work on the 

 MoUusca are freijuently overlooked by conchologists, chiefly because of his 

 reputation as a palaeontologist, though the elaborate memoirs quoted 

 above display the accuracy and profoundness of his knowledge when 

 dealing with either the recent or the fossil aspect of the subject. 



The plan adopted in the preparation of this work has been to give the 



