PREFACE. 



Although this work forms a fifth volume to the " Terrestrial Mollusks 

 of the United States," * I have endeavored to make it a complete manual 

 of the subject. With this view, I have compiled from the writings of 

 my father, my friend Mr. Bland, myself, and other authors all their 

 more important portions, not only of descriptions and figures of species, 

 but of all that relates to the Habits of the Animals, their Geographical 

 Distribution, their Jaw and Lingual Membrane, their Anatomy, and their 

 Classification. I devote no space to Bibliography, referring to my gen- 

 eral work on that subject published by the Smithsonian Institution. 



In the descriptive portion it will be seen that I have usually adopted 

 the descriptions of genera and subgenera of Albers and Von Martens. 

 From the same authors I have also usually adopted the generic and sub- 

 generic names, without inquiry into their precedence, having neither time 

 nor inclination to attempt myself to disentangle the confused synonymy. 



In the synonymy of the species I have quoted only authors giving an 

 original description or an original figure. I have personally consulted 

 all the references, unless otherwise specified. 



The subject is brought down to January, 1878. The plates of Vol. 

 III. are reproduced. Those of Vols. I. and IV. I regret not being also able 

 to give. In the references to plates in the text it must be remembered 



* The Terrestrial Air-breathing Mollusks of the United States and the adjacent 

 Territories of North America : described and illustrated by Amos Binney. Edited 

 by Augustus A. Gould. Boston, Charles C. Little and James Brown. Vols. I., II., 

 MDCCCLI. ; Vol. III., Plates, MDCCCLVII. ; Vol. IV. by W. G. Binney, New 

 York, B. Westermann, MDCCCLIX., from Boston Journal of Natural History, 

 Vol. VII. 



