PREFACE. 



Few branches of Natural History have advanced with more rapidity than that which 

 embraces the part of Malacology which, in this volume, is presented in the form of a 

 Synopsis. This edition is therefore very much enlarged, having quite double the 

 quantity of matter of the former one. The arrangement of the genera will be found 

 to have been somewhat changed. I have added an extensive alphabetic index of species 

 and synonyms, which will be found extremely useful for reference; and the number of 

 additional species will be found to be rather more than that which composed the whole in 

 the previous edition. 



