A TREATISE 



ON 



MALACOLOGY; 



OR 



SHFTT.S AMD SHFT.T.FTSH 



ERRATA. 



Page 192. line 3. from bottom, for "LucideUa" read " Lucidula." 

 193. lines 19. and 36. for " Heraicycla" read " Polygyra." 



CHAPTER I. 



INTRODUCTORY OBSERVATIONS. THE MOLF.USCA IN GENERAL. 



THE CHARACTERS AND ANALOGIES OF THE THREE PRI- 

 MARY DIVISIONS OR classes; NAMELY, THE ACRITA, THE 



RADIATA, AND THE TESTACEA. NOTES ON THE BIBLIOGRAFHY 



AND THE EXISTING CLASSIFICATIONS OF THE LATTER. 



(l.) In our last volume^ we completed the survey of 

 those great divisions of animals which, from possessing 

 a bony skeleton, are called the Vertebrata. Our pre- 

 sent treatise will he devoted to a far more numerous, hut 

 less interesting, assemblage, — namely, the Mollusca, 

 or soft animals. These, with few exceptions, are 

 either inhabitants of the ocean or of fresh waters. The 

 majority are little known even to naturalists ; and 



B 



f 



