PEEFACE BY THE EDITOR. 



My late father had at the time of his death (which took place on Oct. 26th, 1880 

 collected some materials and written the text for a further short Supplement to his 

 original work on the " Crag Mollusca." These materials and text consisted of the 

 descriptions here given, and also of those of the remains of certain vermiform mollusca 

 which he had got together from the Coralline and Red Crag beds. The latter, however, 

 were not left by him in such a form as would allow me to give his views without risk 

 of misrepresentation ; and as I know, moreover, that in respect of one at least of these 

 forms he was in great doubt to the last, whether it belonged to the Molluscous sub- 

 kingdom at all, I have thought it best to suppress that portion of his notes, and to 

 give only the portion which relates to the Gasteropoda and Bivalvia ; as to which I well 

 know what his ideas were. This part forms but an insignificant addition to the pre- 

 ceding portions of his work, and comprises for the most part only shells that have got 

 into the Red Crag beds by derivation from older formations ; but as all such shells 

 must be considered, and eliminated from the evidence which is obtainable to show of 

 what the molluscan Fauna of that part of the North Sea which washed the shore of 

 East Anglia at the time of the Red Crag really consisted, their description and repre- 

 sentation by figure, as my father intended, appear to me to form a proper sequel to his 

 work. 



The text which is not comprised by brackets is that left by my father. The text 

 within brackets (with the exception of the description of Margarita crassi-striata, and 

 of the bed at Boyton from which that shell was obtained, which is by Mr. Robert Bell, 

 is by myself. 



