LYMN^EID^E OF NORTH AMERICA. XIII 



Page. 

 Effect of the Glacial Period on the Lymnseid 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 Lymnseas 85 



Stratigraphical Table of Extinct American Lymnseas 86 



B. Descriptions of American Fossil Lymnseas 87 



Comanchean Lymnseas 87 



Cretaceous Lymnseas 89 



Lower Eocene Lymnseas 95 



Middle Eocene Lymnseas 95 



Oligocene Lymnseas 97 



Middle Miocene Lymnseas 102 



Pliocene Lymnseas 102 



Pleistocene Lymnseas 105 



Doubtful Lymnseas and Species wrongly referred to this 



Family 109 



C. Bibliography of American Fossil Lymnseas Ill 



V. Historical Sketch of Previous Monographs 117 



VI. A New Classification of the Lymnseas 120 



General Discussion 120 



Key to Genera and Subgenera of Recent American Lymnseas 125 



Extralimital Groups of Lymnseinse 127 



VII. Nomenclature 129 



VIII. Instructions for Collecting and Preparing Lymnseas 131 



IX. Systematic Discussion of Species 133 



Family Lymn^eioe Brod 133 



Subfamily LymnjeintE Dall 133 



Genus Lymn^ea 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 sanctcemarice 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 



