PREFACE. 



The following pages are the result of studies in Conchology, 

 pursued as a diversion during the casual moments which inter- 

 vene in the daily routine of business. They are the product of 

 leisure moments in active professional life, — otia, — and, indeed, 

 to no small extent, of moments stolen from sleep. Short papers, 

 from time to time, have been published in several periodicals. 

 Extra copies of the sheets relating to the Shells of the Explor- 

 ing Expeditions under Captains Wilkes and Eodgers were secured 

 as they were originally printed. This will account for the diver- 

 sity of type and paper which appears in the volume. 



To obviate the difficulty of possessing or consulting numerous 

 volumes, I have collected and reprinted, in addition, all the de- 

 scriptions I have hitherto published ; making also such emenda- 

 tions as the advance of science during this lapse of time demands. 



The dates of each imprint will be found at pages 100, 178, or 

 connected with the title of each extract. 



Boston, April, 18G2. 



