TO THE MEMOEY 



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. 



