A 
MONOGRAPH 
OF THE 
FRESH-WATER UNIVALVE MOLLUSCA 
OF THE 
UNITED STATES, 
(IN CONTINUATION OF PROF. 8. 8. HALDEMAN’S WORK, PUBLISHED UNDER 
THE ABOVE TITLE.) 
By GEORGE W. TRYON, Jr. 
TURBIDA, 
PHYSADA. 
PHILADELPHIA: 
PUBLISHED BY 
Tae Concuotogican Section or THE Acapemy or NaturaL Screnczs, 
N. W. corner of Broad and Sansom Streets. 
NEW YORK: é LONDON : 
B. Westermann & Co., 440 Broadway. Tribner & Co., 60 Paternoster Row. 
a BERLIN: MADRID: 
Asher & Co., 20 Unter der Linden. C. Bailly-Bailliere, Calle del Principe. 
PARIS: 
| J. B. Bailliere et Fils, Rue Hautefeuille. 
Lae, sa 
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