DISTRIBUTION OF FOSSIL FRESH-WATER MOLLUSKS
* This work was carried on under the financial support of a grant from the Penrose Fund of The Geological Society of America. To the officers of the Society, my thanks are due. I wish also to extend my thanks to Dr. Carle Dane, Dr. John B. Reeside, Jr., Dr. William W. Rubey, and Dr. J. Steele Williams for their keen criticisms, which indeed improve considerably the contents in presentation. It should be mentioned that the generic nomenclature in a number of species adopted in this paper is in its broad sense, for the convenience of the readers in general.
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