PLATE II 



All original figures except 14 b, 14 c. and 17 « are enlarged three diameters. 



Figs. 1-6 — /'. nevadensis, carinate forms. 

 7-8 — " smooth var. 



9 — " operculum. 



10 — " Outline of Stearns' figure 



in Troc. Phila. Ac. Nat. Sci., p. 173, 

 (1883). 

 II- 12 — Pyrgula helvetica, Mich. 



13 — P. scalariformis — Copy of Wolf's figure 

 in Am. Jour. Conch., Vol. V., pi. xvii., 



fig- 3- 

 14-16 — P. mississippiensis. 

 1 7 - 19 — P. spinosus. 



All figures except 10 and 13 an- drawn from specimens in the authors' cabinets. 



