70 AN ANNOTATED CATALOGUE 



Family SUCCINID.^. 



Succinea ovalis Gould. Abundant. In the northern 

 portion of the state it is replaced by S. higginsi, from which 

 it is often with difficulty distinguished. 



/Succinea obliqua Say. Abundant everywhere. At Des 

 Moines the variety totteniana is associated with this spe- 

 cies. During periods of drought the habits of S. obliqua 

 are similar to those of Mesodon clausus as already given. 



Succinea avara Say. Common. This species and 8. 

 obliqua are abundant in the loss throughout the state. 

 Succinea higginsi Bland. Common in northern Iowa. 



Family AURICULIDJE. 



Carychium exiguum Say. Iowa City, Des Moines : 

 common. Many shells of this minute species are often 

 found abundantly in the drift-wood along the streams. 



Family 



Linncea stagnalis Linnaeus. Spirit and other lakes of 

 northern Iowa, where it is often exceedingly abundant. 



Bulinmea megasoma Say. Winnebago and adjoining 

 counties : common in many of the ponds and pools. 



Limnophysa reflexa Say. Dallas, Dickinson, Hardin, 

 Johnson, Des Moines counties : everywhere abundant. A 

 very large form occurs in great numbers in the prairie 

 ponds of Dallas county. In a marsh a few miles north of 

 Des Moines is found typical L. zebra Tryon ; from which 

 there is a perfect gradation to typical L. reflexa. From 

 near Dubuque has been received a variety that is nearly 

 black. These varietal differences may be regarded as the 

 resultant of different conditions of environment. 



Limnophysa palustris Miiller. Twin Lakes (Hancock 

 county). Lake Okoboji furnishes the variety described 

 as L. nuttaliana, 



