ADVERTISEMENT. 



The opportunity afforded by Mr. Carpenter's visit in 1859-60 

 to the United States, was embraced to secure his services in 

 naming and arranging the shells collected by the United States 

 Exploring Expedition and other parties on the Pacific Coast of 

 North America. Mr. Carpenter, having previoyisly presented to 

 the British Association a report on the state of knowledge in 

 regard to the mollusks of the west coast of North America, 

 embodied the additional information which he obtained, chiefly 

 through the Smithsonian Institution, in a second report to the 

 same Association ; and now, in order to facilitate the study of 

 this class of animals by the American student, this work is re- 

 published with supplementary papers, from stereotype copies of 

 the original pages. 



JOSEPH HENRY, 



Secretary S. I. 

 Smithsonian Institution, 

 Washixgton, November, 1S72. 



phuabelphia: 

 ootLina, PBiHTim. 



