PREFACE. 



This Work was suggested by the perusal of Kirby and 

 Spence's " Introdviction to Entomology," and it is based 

 on some letters which I contributed to Loudon's " Magazine 

 of Natural History," between the years 1829 and 1834. 

 This acknowledgment is necessary, for as the letters were 

 anonymous, a reader might perchance be found to conclude 

 that I had been guilty of plagiarism on rather an extensive 

 scale. 



My object is to present the Conchologist with a view of 

 the economical, physiological, and systematical Relations 

 of Molluscous Animals to each other, and to other created 

 beings. I am not aware of any other Introduction, in the 

 English language, in which this has been attempted ; and 

 therefore my little ambition to occupy the vacant niche in 

 the literature of a favourite department of natural science 

 may be the more excused. I am very sensible that the 

 Essay has not been satisfactorily accomplished ; and it 

 would have been still less so, but for the liberal permis- 

 sion given to me by Mr. Gray to avail myself of some of 

 his valuable writings, the republication of which, in a 

 more accessible form, cannot but be acceptable to the 

 Conchologist. 



