IV PREFACE. 



here figured for the first time. I am also indebted to Mr. 

 John B. Henderson, Jr., of Washington, D. C., who in- 

 trusted to me his rich collection of West Indian Achatinidce 

 and Oleacinidce. Dr. W. H. Dall, whose kindness I have 

 had so often to acknowledge in these pages, granted the use 

 of various types in his custody from the National Museum. 

 For all of these favors I am deeply grateful. H. A. P. 



