290 GEOLOGY. 



Valvata , Say, Otoe and Burt Counties. 



Vivipara intertexta? Say, Otoe County. 



Vivapara subpurpurea? Say, Otoe and Nemaha Counties. 



Vivapara contectoides, Binney, Nemaha County. 



Melantho ponderosa, Say, Washington County. 



Melantho decisa, Say, Burt County. 



Amnicola perata? Say, Washington County. 



Amnicola lemnosa? Say, Washington County. 



Pomatiopsis lapidaria, Say, Dakota County. 



Helicina orbiculata, Say, Nemaha County. 



Angitrema armigera, Say, Nemaha County. 



Lithasia, obovata, Say, Richardson County. 



Pleurocera undulatum? Harlan County. 



Pleurocera canaleculatum, Say, Nemaha County. 



Pleurocera elevatum, Say, Otoe County. 



Pleurocera labiatum? Lea, Richardson County. 



Pleurocera simplex? Lea, Otoe County. 



Goniobasis depygis, Say, Richardson and Otoe Counties. 



Goniobasis livescens? Menke, Richardson County. 



Goniobasis brevispira? Anthony, Otoe County. 



Goniobasis, semicaranata, Say, Otoe County. 



Anculosa costata, Anthony, Richardson County. 



Anculosa praerosa, Say, Richardson County. 



Anculosa? , Richardson County. 



Unio , Cedar, Dakota, and Burt Counties. 



Unio , Nemaha County. 



Unio , Otoe and Cass Counties. 



Anadonta , Washington County. 



Anadonta , Republican Valley. 



