ACKNOWLEDGMENTS 



ACKNOWLEDGMENT is made to Dr. Henry A. Pilsbry, 

 ±\^ Curator of the Department of MoUusca of the Academy 

 of Natural Sciences of Philadelphia, for determination of and 

 information concerning several species of the Pupillidae and 

 other small snails. A student of Dr. Pilsbry in 1889, the author 

 of this fieldbook has been inspired by this dean of American 

 conchologists during a half century of scientific endeavor. It is 

 fitting that appreciation of this guidance be made here. 



Thanks are due to Dr. Harley J. Van Cleave, Professor of 

 Zoology, University of Illinois, for advice and criticism during 

 the preparation of this volume; and to Dr. Allen F, Archer, 

 Museum of Zoology, University of Michigan, for information 

 concerning the status of certain species of Polygyra. 



The author is indebted to Dr. Van Cleave and to his son, 

 Philip, for several collections made in the vicinity of Urbana and 

 in other parts of Illinois; and to Dr. Alvin R. Cahn, formerly 

 Assistant Professor of Zoology, University of Illinois, for ma- 

 terial from a number of places in the state. 



Grateful acknowledgment is made to the memory of Dr. 

 Thural Dale Foster, companion and friend during the survey 

 of the state which preceded preparation of this volume, for not 

 a little of its value is due to his painstaking search for rare or 

 new Illinois records. 



The author acknowledges his indebtedness to the following 

 colleagues: Dr. Carl O. Mohr, Associate Entomologist of the 

 Illinois Natural History Survey, for his painstaking work on the 

 excellent figures which illustrate this manual; Dr. B. D. Burks, 

 Assistant Entomologist of the Survey, for assistance in preparing 

 and checking keys; Mr. James S. Ayars, Survey Editor, for the 

 careful revision of the manuscript and for many suggestions 

 which have made the work of greater value. 



The author wishes to express his deep appreciation to Dr. 

 T. H. Frison, Chief of the Illinois Natural History Survey, 

 through whose interest the moUuscan survey of 1931-32 and the 

 preparation of this fieldbook were made possible. 



Fraxk Collins Baker 



