PREFACE 



Two volumes of the Conehologist's Exchange and thirty-two 

 of The Nautilus are indexed herein. 



John B. Henderson, Jr., realizing the need of some guide to 

 the contents of a series containing much of the work on Ameri- 

 can mollusks for the third of a century, undertook the compila- 

 tion of this index, assisted by his Secretary, Miss Marguerite 

 Woodward. The task was interrupted by his lamented death 

 in 1923. Unwilling to let Henderson's work be lost, Dr. Wil- 

 liam H. Dall completed and edited it, engaging Mr. S. G. 

 Mason to arrange the references. 



More than 80,000 references assembled here give evidence 

 of the arduous labor involved in the compilation and editorial 

 supervision. 



Finally, the months of labor devoted to the task would have 

 been fruitless had it not been for the interest of Dr. George H. 

 Clapp and Dr. Bryant Walker, who made the publication 

 possible. 



H. A. P. and C. W. J. 



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