SUBSCRIBERS. 



Evans, John, Delaware Co., Pa. 



Mifflin, S. W., C. E.. Hybla, 

 York Co., Pa. 



Ward, C. J., M. D., Roscoe, 

 Ohio. 



PENDLETON, la. 

 Fussell, Edwin, M. D. 



DARIEN, Geo. 

 Couper, Hamilton J., Esq. 



PORTLAND, Maine. 

 Mighels, J. W., M. D. 

 Neal, John, Esq. 



MONMOUTH, Maine. 

 True, N. T. 



PROVIDENCE. 

 Rhodes, Robert 



TROY, N. Y. 

 Gates, Elias 



FRANKFORT, Ky. 

 Fall, Rev. P. S. 



BERLIN. 

 Royal Library. 



HAMBURG. 

 Perthes & Besser. 



Hall, James, Albany, N. Y. 



Thompson, , Esq., Liver- 

 pool, Eng. 



Worcestershire Natural His- 

 tory Society, Eng. 



Norris, Thomas, Esq., Bury, 

 Lancashire, Eng. 



Stranger, Dr., Wisbeach, Eng. 



CIRCULAR. 



It is intended that this work shall embrace all our species hitherto 

 described by American and European authors; and as the geographi- 

 cal distribution is a matter of great importance, and one which has 

 not been sufficiently noted, the author will be greatly indebted to 

 those who take an interest in this subject, if they will forward him 

 catalogues of the species, or specimens of the univalve shells found 

 in the streams with which they may be acquainted. 



Descriptions of the animals and their habits would also be very 

 useful; and for any assistance given, acknowledgments will be 

 made. 



Communications may be addressed to the author, at Marietta or 

 Columbia, Pennsylvania, or to the care of Mr. DOBSON, Phila. 



*** No copies of this work will be issued with uncolored plates, 

 or with duplicate plates, colored and uncolored. 



This number completes the genus Physa. Number 7 will be 

 devoted to the genus Planorbis. 



The author has received a beautiful drawing of a living Am- 

 pullaria, executed and presented by J. H. Couper, Esq. of Georgia. 

 He has also drawings from life of Fusus fluvialis, (lo spinosa,) 

 Melania, Anculosa, Amnicola, Valvata, and several other animals, 

 so that there is every probability that he will be able to figure an 

 example of every genus described in this work, and several of them 

 for the first time. 



