PREFACE. 



IT has long been the fashion to present the reader with 

 a prologue ; which, however, I have observed, of late 

 years, has become shorter and shorter. The utility of 

 this practice is questionable, as the body of the work 

 includes all that caa be said in a preface, and by it we 

 forestall the pleasures of expectation ; besides, be it 

 good or bad and the author is frequently not the 

 writer it often unjustly decides the fate of a book, 

 causing a bad one to be read, or a good one to be 

 thrown aside; nevertheless I have in some measure 

 complied with an old custom, by giving a few prelimi- 

 nary remarks in the introduction to the classification. 



It will be observed that some of the families and 

 genera of the Cephalopoda and Pulmonifera have been 

 admitted into the sketch of the classification to com- 

 plete the chain of the Molluscan series; to enter on 

 their consideration forms no part of the plan of this 

 work, which relates exclusively to the British Marine 

 Testaceous Mollusca. 



In some instances " nobis " is attached to the name 

 of well-known species ; this has been done, not from 

 any desire to assume credit for the labours and disco- 



