TO THE MEMORY 



OF 



MANY DISTINGUISHED NATURALISTS 



AND VALUED FRIENDS, 

 WHO ARE NOW NO MORE, 



AND IN GRATEFUL ACKNOWLEDGMENT OF THE 



KIND SYMPATHY OF 



THOSE WHO STILL HAPPILY SURVIVE, 



FROM ALL OF WHOM I HAVE RECEIVED 



MUCH ASSISTANCE 

 IN THESE CONCHOLOGICAL STUDIES, 



I DEDICATE 

 THE PRESENT WORK. 



