OF THE MOLLUSCA OF IOWA. 73 



Campeloma ohesura Lewis. This species is found abiin- 

 duntly in a small creek in Johnson county, a few miles 

 south of Iowa City. 



Lioplax subcarinata Say. Iowa, Cedar and Mississippi 

 rivers : common. 



Family Rissoid^. 



BytJiinella obtusa Lea. Abundant in the bayous adja- 

 cent to the streams at Des Moines, Iowa City and else- 

 where ; in some localities it appears to be quite rare. 



8omatogyrus depressus Tryon. This species was de- 

 scribed by Tryon from specimens obtained from the 

 Mississippi river at Davenport. It occurs abundantly at 

 Eldora, Iowa City and Des Moines. 



Somatogyrus subglobosus Say. Abundant in many of 

 the ponds and streams throughout the state. 



Amnicola limosa Say. Spirit Lake, Iowa City. It is 

 widely distributed through Iowa, Minnesota and contigu- 

 ous states ; and has been collected by Mr. Grant in the 

 Vermillion river. Turner County, Dakota. A. porata 

 doubtless occurs also in the state. 



Amnicola cincinnatensis Anthony. The most abundant 

 and widely distributed species of the genus found iu the 

 state. 



Amnicola orbiculata Lea. Specimens collected in the 

 ponds of Johnson and Polk counties have been referred 

 to this species. 



Pomafiopsis lapidaria Say. Eldora, Des Moines and 

 Iowa City : not common. 



Family Helicinid^. 

 Helicina occulta Say. This species was described by 

 Say from fossil specimens; and, previous to 1876, was 

 known only in that state ; in that year it was discovered 



