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MONOGRAPH 



FRESHWATER UNIVALVE MOLLUSCA 



UNITED STATES. 



(IN CONTINUATION OF PROP. S. S. HALDEMAN'S WORK, PIIBL18HED 

 UNDER THE ABOVE TITLE.) 



By GEORGE W. TRYON, Jr. 



TURBID^. 

 PHYSAD^. 



PHILADELPHIA: 



Publi.shed by 



The Conoholooical Section of the Academy of Natural Sciences, 



N. W. corner of Broad and Sansom streets. 



NEW YORK : LONDON : 



B. Westermann k Co., 440 Broadway. Trubner & Co., 60 Paternoster Row. 



BERLIN : M.^DRID : 



Asher & Co., 20 Unter der Linden. C. Bailly-Bailliere, Calle del Principe. 

 PARIS : 

 •T. B. Bailliere et Fils, Rue Hautefeuille. 



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