Mr. Chadwick, writer of this account of the Williams 

 Collection of Shells, was for many years a practical 

 worker in conchology in the largest establishment of 

 its kind in this country. His scientific knowledge was 

 supplemented by an exceptional opportunity for study- 

 ing this special collection, every case being freely 

 opened to him during the many days he gave to its 

 examination. This careful study makes his report 

 unusually thorough and illuminating. 



