408 The Molluscan Family Plaiwrbidae 



PLATE 86 



Shells of Planorbidae 



I. Hclisoma trivolvis (Say). Indian River, Cheboygan Co.. Michigan. (^ Planorhis. 



megastoma DeKay.) U.I., Z32472. 

 2.4. Heliaoma trivolvis (Say). Salt Fork, near Urbana, Chaniiuugn Co., Illinois. 



{ =^ Planurbis psiudotrivolvis F. C. Baker. 2, paratype; 4, holotype). U.I., 



Z 11292. 

 3. Hclisoma trivolvis (Say). Salt Fork, near Urbana, Illinois. {^= Planorbis pseudo- 



trivolvis F. C. Baker. Type locality.) B930. 

 5-8. Helisoma trivolvis lentum (Say). New Orleans, Louisiana. Type locality. \j.l., 



Z30538. 

 9,10,1^- ficlisotna trivolvis intcrtextum (Sowerby). Manatee Rivor, Florida. U.I., 



Z32367. 



II, 12, 15. Hclisoma trivolvis intcrtextum (Sowb.). Shoal Creek, Alabama. U.I.. Z32365. 

 14. Hclisoma trivolvis intertcxtum (Sowb.). Manatee River, Florida. B1085. 



16. Hclisoma trivolvis chautauquensc F. C. Baker. Chautauciiia Assembly, Chautau- 



ciua Lake, New York. Type locality. U.I., Z27842. 



17. Hclisoma trivolvis chautaucptoisc F. C. Baker. Chavitauqua Lake, New York. 



Holotype. U.L, Z23780. 



18. 19. Helisoma trivolvis chautauqucnse F. C. Baker. Chautauqua Lake, New York. 



Paratypes. U.L, Z23780. 



20. Hclisoma trivolvis (Say). Enlargement of whorls on base. B3914. X7. 



21. Hclisoma trivolvis (Say). {^ Planorbis pseudotrivolvis F. C. Baker). Enlargement 



of whorls on base. B3915. X7. 



22. Hclisoma trivolvis lentum (Say). Enlargement of whorls on base. B3916. X7. 



23. Helisoma trivolvis intcrtextum (Sowb.). F.nlargement of whorls on base. B3917. X7. 



All figures, excepting those indicated otherwise, are 

 enlarged about I73 diameters 



