xii INTRODUCTION. 



logical research, to whom every species of information, although familiar to those 

 long engaged in the study, will be acceptable. 



It has been, of course, my endeavour to make the work as complete as possible, 

 though it merely professes to be a plain and faithful delineation and history of the 

 " Remains of Mollusca from the Crag." I do not pretend to put it forth as free from 

 errors ; on the contrary, it would be surprising if they were not numerous, more 

 especially when it is recollected that in many instances, in consequence of the 

 insufficient materials, and imperfect and altered condition of the shells, a more than 

 ordinary degree of labour is imposed upon the Palaeontologist. 



The figures, in every instance, have been engraved from specimens in my own 

 cabinet, and obtained by myself, excepting where otherwise particularly expressed ; 

 and I beg to return my sincere thanks to my friends for their liberal assistance during 

 the progress of the work ; particularly to Miss Alexander, Mr. Lyell, Capt. Alexander, 

 Mr. Gibson, Mr. Charlesworth, Mr. Daniel, Mr. Perry, Mr. Robert Fitch, and 

 Mr. Wigham, who have allowed me the use of their best specimens for the purpose of 

 comparison and for figuring ; and to Mr. Bean and Mr. Leckenby, for the loan of their 

 specimens from the Bridlington beds. I beg also to express my obligations to several 

 friends who have assisted me with their opinions upon conchological subjects, especially 

 to Professor E. Forbes, Mr. Alder, Mr. Hanley, and Mr. W. Thompson. 



SEARLES V. WOOD. 



January, 1848. 



