INTRODUCTORY 



OBSERVATIONS 



In submitting the third edition of my Catalogue to the Public, in its present form, it is 

 proper to remark, that, owing to its not being in my power to consult some of the works 

 referred to, and, in consequence, being obliged occasionally to copy a reference, there may be 

 errors to be met with ; but, so far as it has been in my power, the References will be 

 found correct. 



The Arrangement pursued is that of Lamarck, with the new Genera of later writers 

 interspersed, in their proper places. Great care has been taken to have the authorities and 

 localities correct; and wherever there was any doubt, a note of interrogation has been 

 placed, and the space left blank ; all which spaces, I trust, some of my friends will enable 

 me to fill. 



It is entirely owing to the generosity of my numerous correspondents, both abroad and 

 at home, that it is in my power to add many species to the present edition ; and I trust that 

 they will consider my returns in as favorable a view. 



The two former editions of this Catalogue having answered the purpose for which they 

 were published, viz., that of presenting to my correspondents and others, in a convenient 

 form, what shells I had, and what I could furnisli in return, I submit the present one to the 

 Public, in the hope, that besides the above object, it may prove of some use. The names 



