PREFACE v 



of Chicago, for kindly criticism and advice. To Mr. Frank Leverett of Ann 

 Arbor, Michigan, and Mr. Frank B. Taylor, of Fort Wayne, Indiana, the 

 author is indebted for information and criticism. The following gentlemen 

 have placed the writer under great obligation by determining the groups of life 

 in which they are specialists. 



Dr. Edward W. Berry, Johns Hopkins University, Baltimore, Md. Plants. 



Dr. Charles A. Davis, United States Geological Survey, Washington (de- 

 ceased). Plants. 



Dr. C. R. Eastman, Carnegie Museum, Pittsburg, Pennsylvania. Fish. 



Dr. C. H. Eigenman, Indiana State University, Bloomington. Fish. 



Dr. O. P. Hay, Carnegie Institute, Washington. Mammals and Fish. 



Dr. A. E. Ortmann, Carnegie Museum, Pittsburg, Penn. Crustacea. 



Dr. R. W. Shufeldt, Washington, D.C. Bird remains. 



Dr. V. Sterki, New Philadelphia, Ohio. Sphasriids. 



Dr. Bryant Walker, Detroit, Michigan. Ancylus, Amnicola and other 

 Mollusca. 



Dr. H. F. Wickham, Iowa State University, Iowa City, Iowa. Insects. 



The gentlemen and institutions whose names appear below have greatly 

 assisted, either by supplying material, publications, data, or advice. 



Dr. C. C. Adams, Syracuse University, N. Y. State College of Forestry. 



Dr. W. H. Dall, U.S. National Museum, Washington, D.C. 



Dr. U. S. Grant, Northwestern University, Evanston, Illinois. 



Dr. T. E. Savage, University of Illinois, Urbana, Illinois. 



Dr. W. W. Atwood, Harvard University, Cambridge, Mass. 



Mr. W. H. Over, Museum, University of South Dakota, Vermillion, S. D. 



Mr. A. W. Slocum, Geological Museum, University of Chicago, Chicago. 



Mr. Ira Meyers, Francis Parker School, Chicago. 



Mr. Henry T. Mortensen, Chicago. 



Mr. A. S. Lewis, formerly superintendent of Lincoln Park, Chicago. 



Canadian Geological Survey, Ottawa, Ontario. 



Chicago Academy of Sciences, loan of plates XXXI, LVI, and LVIII. 



U. S. Geological Survey. 



Green and Sons Company, Chicago. 



Great Lakes Naval Station, Illinois. 



To Mr. Frank M. Woodruff, of the Chicago Academy of Sciences, acknowl- 

 edgment is due for assistance in surveying the North Shore Channel (as well 

 -as in other field work) and for many of the photographs here used as illustra- 

 tions. 



The collections upon which Part I are based have been generously loaned 

 to the University of Illinois by the Chicago Academy of Sciences for study 

 during the preparation of this volume. These are numbers 24300 to 24400 



