406 The Molluscan Family Planorhidae 



PLATE 85 



Shells of Planorbidae 



1-3. Helisoma anceps porlagenac (F. C. Baker). Portage Lake, Aroostook Co., Maine. 



Type locality. B988. 

 4. Helisoma anceps portagense (F. C. Baker). Meach Lake, Quebec, Canada. B3686. 

 5-7. Helisoma anceps latchfordi (Pilsbry). Meach Lake, Quebec, Canada. Type locality. 



Collected by Latchford. U.I., Z37203. 

 8-10. Helisoma anceps percarinatum (Walker). Crystal Lake, Benzie Co., Michigan. 



Type locality. B986. 

 11-13. Helisoma anceps percarhuititm (Walker). Douglas Lake, Michigan. 12 ridged 



shell. U.I., Z26276. 

 14-16. Helisoma anceps cahni F. C. Baker. Big Muskallonge Lake, Vilas Co., Wis- 

 consin. Types. U.I., Z21124. 

 17-19. Helisoma trivolvis (Say). Immature shells. X3. 

 20-24. Helisoma trivolvis (Say). Showing regular increa.se in growth of shell. LT.L, 



Z29134. 

 25-29. Helisoma trivolvis (Say). Braddock's Bay, near Rochester, New York. U.L, 



Z29789. 

 30. Helisoma trivolvis (Say). Elmira, Chemung Co., New York. U.L, Z34976. 



All figures excepting 17-19 are enlarged about 1% diameters 



