412 The Molluscan Family Planorhidae 



PLATP: 88 



Shells of Planorbidae 



1,2. Helisoma trivolvis trivolvis (Say). Presqiie Isle, Michigan. Transition form toward 



macrostomum. U.I., Z26268. 

 3. Helisoma trivolvis trivolvis (Say). Winnebago Lake, near Oshkosh, Wisconsin. Large 



form, but typical. U.I., Z1279L 

 4-6. Helisoma trivolvis macrostommn (Whiteave.s). Mile End Gate, near Montreal, 



Canada. National Museum of Canada. 4, lectotype, 3869; 5-6, paratypes, 



B3870. 

 7. H rlisoma trivolvis macrostomum (Whiteaves). Bayfield, Wisconsin. In beach pool. 



U.I., Z13677a. 

 8-10. Helisoma pilsbryi (F. C. Baker). Tomahawk Lake, Oneida County, Wisconsin. 



Type locality. B843. 

 11-13. Helisoma pilsbryi injracarinatnm F. C. Baker. Rideau River, near Ottawa, 



Canada. B3715. 

 14, 15. Helisoma pilsbryi infracarinatum F. C. Baker. Basswood River Rapids, Rainy 



River District, Ontario. 14, holotype, U.I., Z32361; 15, paratype, B2986. 

 16. Helisoma pilsbryi infracarit^atum F. C. Baker. Basswood Lake, Ontario, Canada. 



U.I., Z41268. 



All figures enlarged about 1V> diameters 



