92 THE NAUTILUS. 



Pyramidula alternata Say. Clay Co. 



Pyramidula cronkhitei Newc. Deuel Co. 



Pyramidula cronkhitei anthonyi Pils. Clay, Pennington and 

 Lawrence Counties. 



Helicodiscus parallelus Say. Clay, Washington, Deuel and 

 Brule Counties. 



Pundum pygmxum Drap. Deuel and Lawrence Counties. 



Punctum californicum Pils. Clay Co. 



Succinea nuttalliana Say. Deuel Co. 



Succinea higginsi Gld. Deuel Co. 



Succinea avara Say. Common over the State. 



Succinea grosvenorii Lea. Common over the plains and prairies. 



Carychium exile H. C. Lea. Stanley Co. 



Carychium exiguum Say. Clay and Deuel Counties. 



Lymnxa elodes Say. Clay Co. 



Lymnxa tryoni Lea. Deuel Co. 



Lymnxa obrussa Say. Black Hills. 



Lymnxa palustris Mull. Generally distributed over the State. 



Lymnxa palustris michiganensis Walker. Deuel Co. 



Lymnsea parva Lea. Perkins and Deuel Counties. 



Lymnxa caperata Say. Common over the State. 



Lymnxa humilis modicella Say. Deuel, Clay, Butte, Perkins 

 and Harding Counties. 



Lymnxa stognalis appressa Say. Deuel Co. Probably over east- 

 ern part of State. 



Lymnsea cockerelli Pils. and Ferr. Over the State. 



Lymnxa techella Hald. Harding Co. 



Physa sayi Tapp. Perkins, Deuel and Harding Counties. 



Physa ancillaria Say. Codington Co. 



Physa humerosa Gld. Spink Co. 



Physa crandalli Baker. Fish ponds at hatchery, Lawrence Co. 



Physa walkeri Crandall (?) Spink Co. Turtle River. 



Physa integra Hald. Rare over the State. 



Physa gyrina Say. Abundant over the State. 



Aplexa hypnorum L. Deuel Co. 



Planorbis umbilicatellus Ckll. Perkins Co. 



Planorbis antrosus Conrad. Locally found over the State. 

 Reported by Audubon in 1840 from Missouri River. Probably 

 at mouth of some creek flowing in from the east. 



