xii The Molluscan Family Planorbidae 



Mr. Paul McGinty, Boynton, Florida 



Dr. Roy W. Miner, Curator, Department of Living Invertebrates, American 



Museum of Natural History, New York City 

 Mr. William B. Marshall, formerly Assistant Curator of Mollusca (Retired), 



U.S.N.M., Washington, D.C. 

 Dr. Paul R. Needham, Associate in Aquatic Biolog}^, U.S. Bureau of Fisheries 

 Mr. Olof 0. Nylander, Caribou, Maine 

 Dr. Henry A. Pilsbry, Curator of Mollusca, Academy of Natural Sciences, 



Philadelphia 

 Dr. C. Ping, Fan Memorial Institute, Peiping, China 



Dr. Baini Prashad, Zoological Survey of India, Indian Museum, Calcutta, India 

 Dr. H. S. Rao, Zoological Survey of India, Indian Museum, Calcutta, India 

 Dr. D. S. Rawson, Professor of Zoology, University of Saskatchewan, Canada 

 Dr. Harold A. Rehder, Assistant Curator, Division of Mollusca, U.S.N.M., 



Washington, D.C. 

 Dr. Horace G. Richards, Academy of Natural Sciences, Philadelphia 

 Mrs. Imogene C. Robertson, Buffalo Museum of Science, Buffalo 

 Dr. Hugo G. Rodeck, Curator, University of Colorado Museum, Boulder 

 Mr. W. F. Shay, Department of Science, Normandy High School, St. Louis 

 Miss Elberta C. Smith, University of Colorado Museum, Boulder 

 Mr. H. W. Smith, Atlantic Coast Biological Station, St. Andrews, New Brunswick 

 Dr. Harley J. Van Cleave, Professor of Zoology, University of Illinois, Urbana 

 Dr. Henry Van der Schalie, University of ^Michigan Museum, Ann Arbor 

 Mr. T. VAN Hyning, Curator, State Museum, Gainsville, Florida 

 Dr. Bryant Walker,* Detroit 

 Dr. Alexander Wetmore, Assistant Secretary, Smithsonian Institution, in charge 



of U.S.N.M., Washington, D.C. 

 Mr. Berlin H. Wright,* Penn Yan, N.Y., and Lakeland, Florida 



The writer is highly appreciative of the help given him by the Uni- 

 versity of Illinois Library, not only for the volumes consulted in its stacks, 

 but also for its aid in securing through the interlibrary loan system many 

 rare volumes not in our own library. To jNIiss Fanny Dunlap the author is 

 deeply indebted for this help. The libraries lending these books include 

 the John Crerar Library, Chicago; Columbia University of New York; 

 Johns Hopkins University, Baltimore; Harvard University, Cambridge; 

 University of Michigan, Ann Arbor; Iowa State College, Iowa City; The 

 U.S. Geological Survey, Washington, D.C; and the Congressional Library 

 of AVashington, D.C. 



The photographs of the shells and the copies from author's works were 

 all made in the Photographic Laboratory of the University of Illinois, 

 under the direction of Mr. Ray R. Hamm, Manager of the Laboratory. 



The author desires to express his deep appreciation of the help given 

 by Dean R. D. Carmichael, of the Graduate School of the University of 

 Illinois, who has greatly aided in the preparation of the work by providing 

 several grants of funds for the making of the photographic plates. Without 

 this assistance this volume could not have been completed. f 



Frank Collins Baker 



*Deceased. 



tThe University of Illinois Press here records its appreciation of the assistance 

 of Professor Harley J. Van Cleave, who, in addition to writing the 'Memorial' and 

 compiling the bibliography attached thereto, has carefully checked the copy and the 

 plates, including the legends, and has given many helpful suggestions on the typo- 

 graphical and scientific arrangement of the data. Mrs. Katharine Hill Paul, artist in 

 the Department of Zoology, has rendered valued service in making numerous altera- 

 tions of the original drawings to ensure satisfactory engravings. — H.E.C. 



