8 INTRODUCTION. 



to the discussion of a subject upon which so much di- 

 versity of opinion exists in the minds of naturalists; 

 but to give an opportunity of comparing, without much 

 trouble, the classification of Linnaeus and La Marck, 

 to those who may be disinclined to purchase an ex- 

 pensive book, or are altogether unacquainted with the 

 language in which it is written, and not perhaps anx- 

 ious to make Conchology a scientific pursuit; thus en- 

 abling them at the same time to keep pace with mo- 

 dern science, by understanding something of the new 

 arrangement. 



La March's generic descriptions have in most in- 

 stances been preserved, but not always literally ren- 

 dered, and frequently others added or substituted, as 

 much as possible divested of the technical terms of 

 science, which are difficult to comprehend, and appear 

 obscure to those not accustomed to compare shells with 

 their written descriptions. 



A catalogue of the recent species is subjoined to 

 each genus in the order established in the original 

 work, the number of fossil species enumerated, and il- 

 lustrative examples selected from the system of Lin- 



