4 LAND AND FRESH WATER MOLLUSKS 



TABLE I. DISTRIBUTION OF FRESH WATER SHELLS NORTH 



OF LATITUDE 49 , ACCORDING TO THE DRAINAGE 



SYSTEMS NOW EXISTING. 



Name of Species. 



Lymnaea stagnalis 



Lymnaea petersi 



Lymnaea atkensis 



Lymnaea megasoma 



Lymnaea emarginata 



Lymnaea binneyi , 



Lymnaea preblei 



Lymnaea columella 



Lymnaea randolphi 



Lymnaea kirtlandiana .... 



Lymnaea truncatula 



Lymnaea humilis 



Lymnaea desidiosa 



Lymnaea galbana 



Lymnaea holbolli 



Lymnaea vahli 



Lymnaea palustris 



Lymnaea reflexa 



Lymnaea catascopium 



Lymnaea adelinae 



Lymnaea? perpolita 



Lymnaea caperata 



Lymnaea anticostiana 



Planorbis bicarinatus 



Planorbis corpulentus 



Planorbis binneyi 



Planorbis trivolvis 



Planorbis campanulatus ., 

 Planorbis var. rudentis.... 



Planorbis exacuous 



Planorbis var. megas 



Planorbis opercularis 



Planorbis var. planulatus . 



Planorbis hirsutus 



Planorbis var. deflectus.... 



Planorbis parvus 



Planorbis vermicularis 



Planorbis nathorsti 



Planorbis arcticus 



Planorbis umbilicatellus .. 



Planorbis crista 



Segmentina armigera 



Segmentina christyi 



Physa heterostropha 



Physa gyrina 



Physa ancillaria , 



Physa lordi 



Physa propinqua 



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