388 ■ Quarterly Journal of Co/uitology. 



P. BiCARiNATUs, Say. Common ; hard to find alive ; seems to 

 spend most of its time on muddy bottoms of nearly all of 

 our ponds. 



P. PARVUS, Say. Common in all ponds where Nelumbium 

 luteum grows. 



Segmentina Wheatlevi, Lea. Common, much like P.bicarlnalus 

 in habitat and habit. I seldom find it alive, but find good 

 specimens floating along margins of ponds. 



AxcYLUS Fuscus, Adams. Muscatine Slough and Keokuk Lake. 

 Not very common; on smooth sticks or logs that have lain 

 in the water a year or more. 



Valvatidae. 



Valvata tricarinata, Say. Abundant in our ponds and sloughs 

 in the woods. A well marked var. with spire elevated and 

 rather more robust than the former with a low spire or 

 none. They do not seem to inhabit the same ponds. 



Viviparidae, 



ViviPARA intertexta. Say. Abundant in Muscatine Slough and 

 found sparingly in several other ponds and sloughs. Young 

 shells covered with short hairs in regular rows and 

 seemingly crossing each other, giving the appearance of a 

 woven fabric ; some shells have a slight tendency to bands 

 running with the sutures ; mature shells dark-brown, or 

 black. 



Melantho subsolida, Anthony. Abundant in Mississippi river 

 and Muscatine Slough. I find the shells from the ponds 

 and sloughs to differ slightly from those in the river, yet 

 I can hardly believe there is a specific difference. It 



