O LAND AND FRESH WATER MOLLUSKS 



TABLE I. DISTRIBUTION OF FRESH WATER SHELLS NORTH 

 OF LATITUDE 49°, ACCORDING TO THE DRAINAGE 



SYSTEMS NOW EXISTING. — Continued. 



Name of Species. 



Margaritana var. falcata 



Unio complanatus 



Quadrula plicata 



Quadrula undulata 



Quadrula heros 



Quadrula lachrymosa 



Quadrula rubiginosa 



Sphserium simile 



Sphferium striatinum 



Sphaerium solidulum 



Sphaerium stramineum 



Sph^srium rhomboideum 



Sphaerium walkeri 



Sphasrium fabale 



Sphserium occidentale 



Spha;rium patella 



Sphserium emarginatum 



Sphserium tumidum 



Sphserium spokani 



Sphasrium raymondi 



Sphajrium partumeium 



Sphserium jayanum 



Sphserium tenue 



Spha;rium transversum 



Sphferium truncatum 



Sphaerium lenticulum 



Corneocyclas virginica 



Corueocyclas idahoensis 



Corneocyclas scutellata 



Corneocyclas sequilateralis . 



Corneocyclas compressa 



Corneocyclas variabilis 



Corneocyclas abdita 



Corneocyclas ventricosa 



Corneocyclas rotundata 



Corneocyclas steenbuchi 



Corneocyclas occidentalis... 

 Corneocyclas ultramontana. 



Corneocyclas arctica 



Corneocyclas nivalis 



Corneocyclas glacialis 



Corneocyclas pulchella 



Corneocyclas henslowana... 



