OP CONCHOLOGY, 159 



3. Polygyra septemvolva, Say. 



Plate 11, figure 22. 



Shell discoidal, with seven whorls, which are closely ribbed- 

 striate above, the periphery subangular ; smooth below, and ex- 

 hibiting about four whorls besides those forming the walls of the 

 rather large umbilicus. Horn color. 



Diam. 14, height 3-5 mill. 



Florida. 



4. Polygyra Carpenteriana, Bland. 



Plate 11, figures 23, 24. 



Subdiscoidal, spire slightly elevated ; whorls 5| to 6J, thin, 

 shining, closely obliquely ribbed above, smooth beneath the 

 angular periphery ; base showing 2| whorls, with a minute per- 

 foration. Light horn color or rufous, with frequently opaque 

 irregular bands crossing the whorls. 



Diam, 8—10, alt. 3—4 mill. 



East Florida. 



5. Polygyra VOlVOXis, Parreyss. 

 Plate 11, figure 25. 



Spire a little elevated ; whorls 7, flattened above, convex be- 

 neath, the periphery carinate ; upper surface and base near the 

 aperture closely ribbed, the balance of the base smooth ; over 

 two whorls visible below, besides a narrow umbilicus. Horn 

 color, with frequently white blotches or bands running across 

 the whorls. 



Diam. 9, alt. 4 mill. 



East Georgia and Florida. 



This is perhaps a young state of P, septemvolva^ Say. 



