OF THE MOLLUSCA OF IOWA. 71 



Limnophysa desidiosa Say. Abundant everywhere. 



Limnophysa capera ta Say. Abundant in the ponds and 

 prairie marshes throughout the state. 



Limnophysa pallida Adams. A few specimens, col- 

 lected in Johnson county, have been referred to this spe- 

 cies. It is said to be very abundant at Muscatine. 



Limnophysa humilis Say. Des Moines, Cedar Rapids 

 and elsewhere : common in the marshes. 



PhysagyrinaSay. Everywhere abundant. This species 

 was described from specimens collected in Bowyer creek 

 near Council Bluffs ; it has a very wide geographical dis- 

 tribution and presents a great variety of forms. Typical 

 P. hildrethiana has been collected in abundance in the 

 prairie ponds of Dallas county ; and the form described 

 by Lea as jP. elliptica occurs in great numbers in some of 

 the ponds near Des Moines 



Physa heterostropha Say. Abundant everywhere 

 throughout the state. 



Bulinum hypnorum Linnaeus. Winnebago county and 

 northern Iowa generally : common. 



Planorbella campanulatus Say. Twin Lakes, Hancock 

 county ; Spirit Lake, Dickinson county : quite common. 



Helisoma trivolvis Say. Spirit Lake, Forest City, Des- 

 Moines, Fort Madison, Ottumwa : abundant. 



Helisoma bicarinatus Say. Muscatine, Iowa City, Spirit 

 Lake : common. 



Menetus exacutus Say. Common in the prairie ponds 

 of Central and eastern Iowa. 



Gyraulus deflectus Say. Lake Okoboji ; ponds of Polk 

 and Scott counties. 



Gyraulus parvus Say. Common in Polk and Dickinson 

 counties, and Iowa generally. 



Gyraulus albus Miiller. Davenport, Des Moines : rather 

 common. 



