VI PREFACE. 



has been confined to the very imperfect bounds of the last edition 

 of the Si/sterna JS'aturce. 



And as, like the division of labor, classical arrangement pre- 

 tends to nothing more than that, by clear and consecutive deduc- 

 tion, the several distinct subjects should be brought to nominative 

 identity, passing through the direct genealogy of their several 

 Kingdoms, tribes, orders, and families : whether these ends be 

 etiected through natural alliances or artificial combinations, it does 

 not appear to be of much importance, supposing them to be equally 

 comprehensive, communicable, and demonstrable. 



But in pursuit of a natural arrangement, the neoteric writers of 

 the French school have constituted the organs of the animal as 

 the primary and essential base, making the shell a secondary 

 object of consideration, and absorbing Conchology into a minor 

 branch of Helminthology ; a connexion which must suppose more 

 of tradition and gratuitous admission than of demonstration, and 

 which in our present very imperfect knowledge of the Vermes, 

 we consider to be unnecessary if it were possibe, and impossible 

 if it were necessary. 



We have attempted an arrangement upon principles easily 

 communicable, and strictly demonstrable, which, like the sys- 

 tems of Botany and Zoology, are certainly artificial, but which, 

 on a comparison with the natural connexions of Lamarck and 



