42 POLYGYRIDAE 



9. Parietal denticle quadrate, but not wider than high, 



forming a letter U dorfeuilliana, p. 44 



Parietal denticle long, narrow, not forming a letter U, 

 pp. 45, 62; or quadrate and twice as wide as high, p. 46. . 10 



10. Shell less than 34 inch in diameter; umbilicus small, deep, 



partly closed by reflected lower lip; parietal denticle long, 



narrow leporina* p. 62 



Shell Yi inch in diameter; umbilicus not partly closed by 

 reflected lower lip; parietal denticle quadrate or pyrami- 

 dal, pp. 45, 46 .' 11 



11. Spire dome shaped; parietal denticle quadrate, twice as wide 



as high; space between labial denticles as deep as wide. . 



fraudulenta, p . 46 



Spire flattened; parietal denticle pyramidal, roundly pointed 

 at end; space between labial denticles wider than deep, 

 p. 45 12 



12. Denticles on outer lip or peristome widely spaced, parietal 



denticle pointing between them. . . .tridentata tridentata, p. 45 

 Denticles on outer lip or peristome not widely spaced, pari- 

 etal denticle pointing to labial denticle 



tridentata frisoni^ p. 45 



13. Shell approximately 1 inch in diameter 14 



Shell approximately 3^ inch in diameter 16 



14. Spire encircled by a wide brown hand. profunda profunda, p. 48 

 Spire without a brown band, shell uniformly yellowish 15 



15. Umbilicus narrow, partly concealed by lower lip 



thyroidus, p. 56 



Umbilicus wide, not at all concealed by lower lip 



profunda efasciata, p. 48 



16. Spire dome shaped; umbilical opening very small and partly 



concealed by lower lip clausa, p. 57 



Spire almost flat; umbilicus wide and deep, not at all con- 

 cealed by lower lip tridentata edentilabris, p. 45 



17. Lower lip of shell not notched, p. 51 18 



Lower lip of shell with a notch in middle, p. 59 34 



18. Parietal wall of shell without denticles, p. 51 19 



Parietal wall of shell with denticles, p. 50 25 



19. Shell with color bands encircling whorls, p. 51 20 



Shell without color bands encircling whorls 21 



20. Upper and lower margins oi aperture almost parallel; shell 



1 inch in diameter midtHineata multilineatay p. 51 



Upper and lower margins of aperture diverging toward 

 columellar region; shell approximately } 2 inch in diameter 

 multilineata algonquinensis, p. 51 



*This species may belong to the genus Lobosculum Pilsbry, 



