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 Speci< 



Lymnsea stagnalis 



Lymnsa petersi 



LymoEea atkensis 



Lymnsea megasoma 



Lymnjea emarginata 



Lymnrea binneyi 



Lymn^ea preblei 



Lymn^ea columella 



Lymnaea randolphi- 



Lymnrea kirtlandiana .... 



Lymnaea truncatula 



Lynin£ea humilis 



Lymnaja desidiosa 



Lymn^ea galbana 



Lymncea holbolli 



Lymnaea vahli 



Lyranaea palustris 



Lymnrea reflexa 



Lymnxa catascopium 



Lymnaea adelince 



Lymniea? perpolita 



LymnDea caperata 



Lymnsea 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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