The Mollusca of Eastern Iowa. 71 



taken for P. parvus. Thus far its presence has been ascer- 

 tained only near Davenport and at Iowa City. 

 P. albus. — Mucll. 



A few specimens from the northern part of the state, which 

 are in our collection, probably belong to this species. 

 P. PARVUS. — Say. 



Very common. Great numbers may often be taken in 

 ponds, if one but has the patience to wait for them to come to 

 the surface to breathe, when they float about very much as 

 Physas do. 



The species of Limmva, Physa, and Planorbis are still in 

 a state of confusion. There is so much variation in these 

 fresh-water forms that it is practically impossible in some 

 cases to draw specific lines, and-it will continue so no doubt 

 until a thorough study is made of the dentition and soft parts. 



Genus Segment ina. — Flem . 

 S. ARMIGERA. — Say. 



Locally common in ponds throughout the state, Often cal- 

 led vjheatleyi. 



S UB-FAMIL r~A NC l^LIN.^. 



Genus Ancyltis — Geof. 

 A. DIAPHANUS. — Hald. 



Quite common on sticks, etc., in some of the larger ponds 

 or sloughs. 



A. PARALLELUS. Hald. 



A few were found near Iowa City with the preceding. 



A. RivuLARis. — Say. 



Exceedingly common on stones and shells in ponds and 

 streams. 



Genus Gundlachia — Pfr. 



G. MEEKIANA.— J^/m/. 



While this species has not been found in Iowa, Mr. Pilsbry 

 discovered it in a pond near Rock Island. It is very probable 

 that it occurs on the Iowa side of the Mississippi also. 



