THE TERRESTRIAL 



AIR-BREATHING MOLLUSKS 



OF THE 



UNITED STATES. 



VOLUME IV. 



THE following pages are devoted to a continuation of 

 the work of my father on the Terrestrial Mollusks of the 

 United States. They are believed to contain all the latest 

 information regarding the several species, their varieties, 

 synonymy, geographical distribution, &c. I have also 

 added many references to authors not quoted in the Mol- 

 lusks, as well as to those whose works have appeared 

 more recently. Descriptions of all the newly discovered 

 species are added, and figures given of all to which I have 

 been able to obtain access. 



Since no species was described in the " Mollusks," with 

 which the author or the able editor was not personally 

 acquainted, there were quite a number of doubtful species 

 entirely omitted in that work. These I have added, with 

 all the information in regard to them which I have been 

 able to obtain. 



In addition to the species recently discovered, there are 

 many shells which have been described as distinct species 

 during the last twelve years, though considered as only 



1 The plates are numbered in continuation of those in the third volume of the 

 "Terrestrial Mollusks," by Dr. Amos Binney; as the paper forms a continuation 

 of that work. 



1 



