xii INTRODUCTION. 



tological 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 insuffi- 

 cient 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 B. Forbes, Mr. Alder, Mr. Hanley, and Mr. W. Thompson. 



SEARLES V. WOOD. 



January, 1848. 



