34 
Plate IV 
Figures 1-4. Helisoma corpulentum (Say). Lac la Croix. U.I., Z32626, 
Figures 5 8. Helisoma cor pul cut mu vermilionense F. C. Baker. Vermilion lake, Minn. 
U.I., Z32627. 
Figures 9—12. Helisoma corpulent am multicostatum F. C. Baker. Kalniipiminanikok lake, 
Out. U.I., Z32628. 
Figures 13-14. Helisoma ichiteavesi F. C. Baker. Lae des Mille Lacs, Out. U.I., Z32312. 
Figures 15-1(3. Helisoma infraear inatum F. C. Baker. Lac des Mille Lacs swamp. 
U.I., Z32629. 
Figures 17-19. Helisoma trivolvis (Say). Genesee river, N.Y. U.I.. Z29130a. 
Figure 20. Helisoma infracarinatum F. C. Baker. Lac des Mille Lacs swamp. U.I., Z32629. 
Figure 21. Helisoma corpulentum multicostatum F. C. Baker. Lac des Mille Lacs swamp. 
U.I., Z32312. 
Figures enlarged 2 diameters. Immature. 
