458 The Molluscan Family Planorhidae 



PLATE 111 



Shells of Planorbidae 



1-5. Hclisoma camptuiulatuin rudentis (Dall). Knee Lake, Manitoba, Canada. Para- 

 types. U.S.N.M., 365574. 



6,7. Helisoma carnpanidalum michiganense F. C. Baker. Marl Lake, Roscommon Co., 

 Michigan. 6, holotype, B1809; 7, paratype, B1809a. 



8,9. Helisoma cainpaitidatum michiganense F. C. Baker. Marl Lake, Roscommon 

 Co., Michigan. U.S.N.M., 173102. 



10, 11. i/(7i.som« campauulatum ))iichiganeyise F. C. Baker. Marl Lake, Michigan. 

 U.S.N.M., 173102. 



12,13. Helisoma campanulatinn dalli F. C. Baker. Anticosti Island, Canada. 12, holo- 

 type; 13, paratype. U.S.N.M., 162724. 



14. Hclisoma campanulatum michiganense F. C. Baker. Marl Lake, Michigan. Ab- 

 normal. U.S.N.M., 173102. 



15,16. Helisoma campanulatum dalli F. C. Baker. Anticosti Island, Canada. Para- 

 types. U.S.N.M., 162724. 



17-19. Helisoma campanulatniii colUnsi F. C. Baker. Cameron Lake, Lake of the 

 Woods, Ontario, Canada. 17, holotype; 18, 19, paratypes. U.I., Z41297. 



20. Helisoma campanulaUim collinsi F. C. Baker. Cameron Lake, Lake of the Woods, 

 Canada. Paratype. A small specimen. U. I., Z41297. 



21,22. Helisoma catnpanulatum (Say). Crooked Lake, Emmet Co., Michigan. Young. 

 B3868. X31/2. 



23-31. Helisoma scalare (Jay). Everglades, Florid;i. Marl bed 10-15 ft. under peat. 

 Variation toward seminole form. LT.S.N.M., 348566. 



32. Hclisoma duryi seminole Pilsbry. Lake Apopka, Florida. Showing advanced lower 

 part of aperture in contrast with the receding aperture of scalare (fig. 31). 

 U.S.N.M., 566570. 



All figures, excepting 21 and 22, are enlarged about 1% diameters 



