10 THE CHICAGO ACADEMY OF SCIENCES. 
are in millimeters and the numerals following the former are the 
accession numbers of the specimens in the museum of The 
Chicago Academy of Sciences. In the description of the 
species, the diagnosis of the shell and animal refers only to 
specimens found in this area. Distribution and geological dis- 
tribution signify their dispersal throughout time and space, out- 
side of as well as within our territory. Habitat refers only to 
the area covered by this report. 
The following collections have been examined in preparing 
these pages: Mr J. H. Ferriss, Joliet; Mr. T. Jensen, Chicago; 
Prof. W. K. Higley, Chicago; and the local collection of | 
The Chicago Academy of Sciences, which numbers about 4,000 
specimens, representing almost every prominent locality in the 
area. ‘The writer has personally collected in all parts of the 
territory, and very few notes of station or locality have been 
accepted until personally examined. The writings of Messrs. 
Call, Prime, Pilsbry, Simpson, Tryon, Haldeman, Stimpson, etc., 
have been freely used for information, and the source of such 
information has been indicated in the text. 
The writer wishes especially to acknowledge his indebted- 
ness to the following persons, who have given him very much 
valuable assistance and advice: 
Prof. Henry A. Pilsbry, Conservator, Conchological Section, 
Academy of Natural Sciences, of Philadelphia, Penn., who has 
identified the Amnicole, Ancyli, etc.; Mr. Charles T. Simpson, 
Department of Mollusks, United States National Museum, 
Washington, D. C., who has revised the Unionide, identifying 
many of them as well as a number of gastropod mollusks; Prof. 
R. Ellsworth Call, Superintendent of Schools, Lawrenceburg, 
Ind., who has identified many of the Unionide and all the Cam- 
pelome; Dr. V. Sterki, New Philadelphia, Ohio, who has exam- 
ined the Pupe, Spheria and Pisidia, and given valuable notes 
on their classification. The following persons have also very 
materially assisted, either by notes, advice or specimens: Mr. 
Charles W. Johnson,Curator, Wagner Free Institute of Science, 
Philadelphia, Penn.; Dr. W.S.Strode, Lewistown, Ill.; Mr. Wit- 
mer Stone, Conservator, Ornithological Section, Academy of 
Natural Sciences, of Philadelphia; Messrs. J. H. Ferriss and 
J. H. Handwerk, Joliet, Ill.; Mr. Paul Bartoch, United States 
National Museum, Washington, D. C.; Prof. W. K. Higley, 
Messrs. Frank M. Woodruff, T. Jensen, Paul Favour, Otto 
Spiedel, C. S. Raddin, C. M. Higginson, W. W. Calkins, Carl 
