92 THE NAUTILUS. 



Pyramidula alternata Say. Clay Co. 



Pyramidula cronlhitei Newc. Deuel Co. 



Pyramidula a'onkhitei anthonyi Pils. Clay, Pennington and 

 Lawrence Counties. 



Helicodiscus j)arallelus Say. Clay, Washington, Deuel and 

 Brule Counties. 



Punctum pygmseum 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. 



Lymnaea elodes Say. Clay Co. 



Lymnsea iryoni Lea. Deuel Co. 



Lymnsea obrussa Say. Black Hills. 



Lymnsea palustris Mull. Generall}' distributed over the State. 



Lymniea palustris michiganensis Walker. Deuel Co. 



Lymnsea parva Lea. Perkins and Deuel Counties. 



Lymnsea caperata Say. Common over the State. 



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

 and Harding Counties. 



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

 ern part of State. 



Lymnaea cockerelli Pils. and Ferr. Over the State. 



Lymnaea 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 hypnonim L. Deuel Co. 



Planorhis 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. 



