OF NORTH AMERICA. XIII 



Page. 

 Effect of the Glacial Period on the Lymnaeid Fauna of 



America 75 



Post-glacial and Pre-glacial Species 77 



C. Bibliography of Works Consulted 79 



IV. Distribution in Time 80 



A. General Discussion 80 



Systematic Table of Extinct American Lymnaeas 85 



Stfatigraphical Table of Extinct American Lymnaeas 86 



B. Descriptions of American Fossil Lymnaeas 87 



Comanchean Lymnaeas 87 



Cretaceous Lymnaeas 89 



Lower Eocene Lymnaeas 95 



Middle Eocene Lymnaeas 95 



Oligocene Lymnaeas 97 



Middle Miocene Lymnaeas 102 



Pliocene Lymnaeas 102 



Pleistocene Lymnaeas 105 



Doubtful Lymnaeas and Species wrongly referred to this 



Family 109 



C. Bibliography of American Fossil Lymnaeas Ill 



V. Historical Sketch of Previous Monographs 117 



VI. A New Classification of the Lymnaeas 120 



General Discussion 120 



Key to Genera and Subgenera of Recent American Lymnaeas 125 



Extralimital Groups of Lymnaeinae 127 



VII. Nomenclature 129 



VIII. Instructions for Collecting and Preparing Lymnaeas 131 



IX. Systematic Discussion of Species 133 



Family LYMN^EID^: Brod 133 



Subfamily LYMN^IN^E Dall 133 



Genus LYMN^A Linne 134 



L. stagnalis Linne 136 



L. stagnalis appressa Say 137 



L. stagnalis perampla Walker 151 



L. stagnalis wasatchensis Hemphill 152 



L. stagnalis lilliance Baker 153 



L. stagnalis sanctamarice Walker 156 



L. stagnalis occidentalis Hemphill 160 



L. lepida Gould 161 



Genus PSEUDOSUCCINEA Baker 162 



P. columella (Say) 163 



P. columella chalybea (Gould) 171 



P. columella casta (Lea) 174 



P. columella championi (Von Martens) 175 



P. francisca ( Poey) 176 



Genus RADIX Montfort 178 



R. auricularia (Linne) 179 



