

INTRODUCTION. 



Taking this view of the science of conchology, it will be conceded 

 that it points to objects of the highest importance, a thorough know- 

 ledge of our cosmogony. 



In the investigation of the Naiades it has been frequently a matter 

 of great regret to me, that opportunities have not afforded the means 

 of examining further than I have been able to do into their habits and 

 anatomy. The species within our reach here, are usually small, while 

 many of those inhabiting our western waters are of great magnitude, 

 and must afford, to those who can watch their habits and examine 

 their structure, many curious and interesting facts in connection with 

 their history. 



I believe it has fallen to the lot of no naturalist to have made so 

 great an accession to this family as will be found in these memoirs ; 

 and to have obtained so many not before known has been the com- 

 bined result of industry and good fortune. 



The cabinet of Naiades, of which these form a small part, consists 

 in all of about one thousand nine hundred and fifty specimens, each 

 one selected for its variety of form, colour or age. It includes one 

 hundred and seventy distinct species, comprised in seven genera. The 

 whole have been brought together within about eight years ; and are 

 from almost every important river in foreign countries as well as in 

 this. 



