ADVERTISEMENT 



THE FOURTH EDITION. 



AN this Edition the new species recently discovered have 

 been added; and a considerable alteration has been made 

 in the arrangement of the species of each genus, with a 

 view to afford greater facility to the student's acquiring a 

 knowledge of their distinctive characters. 



IT would have been beyond the scope of an elementary 

 work of this nature to have described every species ; but we 

 have endeavoured, by forming numerous divisions and fa- 

 milies, and affixing to each a concise description, so to 

 class together the species, that the student will have little 

 difficulty in assigning any shell that may present itself to 

 his observation to its proper division and family; and 

 should the shell have obtained a name descriptive of a 

 leading character, he will have no difficulty in discovering 

 it by referring to the lists of scientific and English or tri- 

 vial names accompanying the genera. 



