# Land Mollusca of North America (north of Mexico)/Preface (Volume I)

PREFACE
More than fifty years have passed since publication of the last general work upon land mollusks of the United States and British America, W. G. Binney's Manual of American Land Shells, 1885. I believe that no one publishing work on our land mollusks at that time is still living. The progress of a generation of malacologists is thus to be recorded here, in addition to a summary of the previous work which we inherited.
In the limits set for this work, it is not possible to cover all aspects represented in the work of many naturalists during the past half century. Only the fundamental subjects, description, classification and distribution of our land snails are treated somewhat fully. The Helicacea, comprising more than half of the species and subspecies of our fauna, form the subject of the present volume.
American land snails have been a favorite study with me since boyhood; during most of that time chiefly as an occupation of evenings and in the intervals of other work. A field acquaintance with them, begun as a student in Iowa, has been continued in vacations and collecting trips in the southern Appalachians, the Ozark region of Missouri and Arkansas; in Oklahoma, Texas, New Mexico, Arizona and many other states. But in much of the territory covered in this book, materials were gathered chiefly by friends and correspondents. Among these I may mention especially, Mr. James H. Ferriss, who shared his collections with the Academy, and Dr. H. Burrington Baker, whose work in the southern Appalachians and in Montana, Idaho and Oregon, generously placed at my disposal, has greatly extended our facilities. In the mountain states we have had many contributions from the late Professor Junius Henderson and from Professor T. D. A. Cockerell. In California, Mr. Allyn G. Smith and George Willett were especially helpful. Mr. E. P. Chace and Mrs. Chace supplied valuable material, and Dr. S. S. Berry contributed paratypes of many species. Dr. A. F. Archer gave series of his extensive collections from Michigan to Alabama, and Mr. John P. Oughton supplied Canadian material. Many others, whose names appear in the text, have assisted with particular species or essential data.
​I am also indebted for information and the loan of precious typo material to Dr. Paul Bartsch of the National Museum, Mr. William J. Clench of the Museum of Comparative Zoology, Dr. G. Dallas Hanna and Leo G. Hertlein of the California Academy of Sciences, Dr. Frank C. Baker, University of Illinois, Dr. Stanley T. Brooks, Carnegie Museum, and Mr. Calvin Goodrich, Museum of Zoology, University of Michigan. Dr. Bernard Rensch lent type material from the Zoologisches Museum in Berlin, and Lieut.-Col. A. J. Peile compared various specimens with types in the British Museum. The book is much the better for this friendly cooperation.
In the Academy the long task of preparing the work has been constantly encouraged by the President, Mr. C. M. B. Cadwalader, whose interest made the publication possible. Mr. J. A. G. Rehn, Chairman of the Publication Committee, gave liberally of his time and expert knowledge of engraving and printing. Mr. V. S. L. Pate assisted in preparing the manuscript for the press. In the proofreading I owe much to Mr. C. Bernard Peterson's accurate eye. He also prepared the Index.
Finally, the illustrations of shells, which, in a descriptive work on mollusks are considered as essential as the text, have mostly been prepared by Miss Helen Winchester, whose collaboration has been indispensable to the usefulness and the appearance of the work.