PREFACE. 



The kind reception given to my little book on the "Common 

 Sea-shells of California, ' ' has induced me to prepare this larger 

 work, embracing a wdder territory, namely, that part of the United 

 States lying west of the Rocky Mountains. 



The present volume includes descriptions of all the species men- 

 tioned in the former one, together with many others of the more 

 minute and uncommon marine shells which are found from Puget 

 Sound or Alaska on the north, to San Diego on the south. 



It also describes the land and fresh-water mollusks of California, 

 Oregon, Washington, Idaho, Utah and Nevada, thus making it of 

 use as a reference-book for the interior, as well as along the 

 sea-coast. 



While not claiming absolute completeness, I trust it will be 

 found sufficient to enable students and collectors to identify all the 

 specimens which they will be likely to gather within the limits 

 already mentioned. 



The nearly two hundred engravings have all been drawn from 

 nature, expressly for this work, and while materially increasing 

 its cost, they will, I trust, even more increase its value. 



Some additional matter respecting the authors of the specific 

 names, a Glossary, and a brief Key for the Analysis of Shells, will 

 be found near the close of the book. 



The work is written in a familiar style, but is believed to be 

 scientifically accurate. Though containing many hard names and 



