416 The Molluscan Family Plauorbidae 



PLATE 90 



Shells of Planorbidae 



1-4. Helisoma (runcatum (Miles). Saginaw Bay, Michigan. Type locality. U.I., Z32515. 

 5-8. Helisoma truncatuui (Miles). Spirit Lake, Iowa. U.S.N.M., 476566. 



9. Helisoma truncatum (Miles). Spirit Lake, Iowa. U.S.N.M., 505847. 



10. Heluoma truncatum (Miles). Sturgeon Bay, Door Co., Wisconsin. U.I., Z18455. 

 11,12. Helisoma truncatum (Miles). Winnebago Lake, Wisconsin. U.I., Z12805. 

 13-15. Helisoma subcrenatum disjectum (Cooper). Tuolumne, California. B1090. 

 16-18. Helisoma subcrenatum disjectum (Coojier). Boise, Idaho. LT.L, Z36335. 

 19-21. Helisoma subcrenatum horni (Tryon). Paul Lake, British Columbia. B3148. 

 22-24. Helisoma subcrenatum variety? Quamichan Lake, British Cohmibia. B1973. 



All figures are enlarged a little less than two diameters 



