4 PREFACE. 



As this may fall into the hands of conchologists, we would like 

 to ask a few questions, especially in relation to the interesting 

 family Unionidce. 



What is known about the sex ? We are led to believe they are 

 hermaphrodite, with neutrals. 



How do the muscular impressions change as the mollusk grows ? 

 For example : in a young A. grandis the anterior and posterior 

 adductors may be less than an inch apart ; eventually they are 

 more than six inches apart. How does this occur ? 



Does the form of a shell alter with age ? 



Is there a period of maturity ? How long do they live ? What 

 is the nature of their food ? 



These questions may all have been fully explained ; but we have 

 seen nothing satisfactory. 



In the study of our rnollusca, we have used the following works 

 in the library of F. M. Witter, and numerous exchanges of shells 

 from various parts of the United States. Lea's Naiades, from 

 " Philadelphia Transcript ; " " Observations on the Genus Unio," 

 the last six volumes, and " Synopsis of the Family Unionidse," of 

 1870; "American Conchologist," seven volumes; "Monograph 

 of the Unionidse," by Conrad; "Monograph of the Terrestrial 

 Mollusca of the United States," by George W. Tryon, jun. ; 

 " Mollusca of New York," by James E. DeKay ; "Land and 

 Fresh- Water Shells of North America," Parts I., II., III., and 

 IV., Smithsonian publication; "American Conchology," Say; 

 " Recent and Fossil Shells," Woodward ; " Treatise on Shells and 

 Shell-Fish," by Swainson ; " Conchologia Cestrica," Hartman & 

 Michener ; " Turton's British Shells," by J. E. Gray ; " Land and 

 Fresh- Water Shells of La Salle County, 111.," by W. W. Calkins ; 

 and various local lists and reports in government surveys. 



We desire to express our thanks to Dr. R. M. Byrnes of Cin- 

 cinnati, O. ; Dr. James Lewis of Mohawk, N. Y. ; Professor George 

 W. Tryon, jun., Philadelphia; Professor John W. Taylor, Leeds, 

 Eng. ; and man}^ other gentlemen with whom we have corre- 

 sponded, and exchanged specimens. The following is a list of 

 those who have been or are now connected with our club : F. M. 

 Witter and daughter Anna, George Moore, Albert Knoblauch, James 

 Stockdale, William L. Roach, Charles Braunwarth, Fred. Green, 

 John Fogarty, John Dobbs, Isaac Mathewson, Emanuel Daniels. 



