[S2] 



12. Mesodon Mitchelliana, Lea. 



Plate 8, figure 10. 



Subglobose, moderately thick, translucent, finely striate ; 

 spire convexly conical, suture not deeply marked ; wliorls 5, 

 the last well rounded, contracted behind the lip above, but the 

 groove becoming indistinct towards the base ; aperture rounded, 

 lip white, narrowly reflected ; base very convex, imperforate. 

 ■Light horn color. 



Diam. 15, height 9 mill. 



Found only in Ohio. 



For the distinction between M. Pennsylvanica and this 

 .species, see the description of the former. 



13. Mesodon divesta,. Gould. 



Plate 8, figure 11. 



Depressed orbicular, moderately thick, coarsely obliquely 

 .striated ; spire a little convex, with well-marked suture ; whorls 

 (), the last subangulate at the periphery ; aperture lunate, very 

 oblique, lip white, broadly reflected, horizontal at base, its 

 •outer portion flexuous ; base convex, umbilical region ex- 

 cavated, but covered. Dingy horn color. 



Diam. 18, height 7 milk 



Washington Springs, Arkansas. Coll yC .Q .di , 



Distinguished by its depressed form. Although described 

 mearly twenty years ago, no other locality than that above 

 given has been discovered. ^ 



W Banded. 

 14. Mesodon multilineata, Say. 



Plate 8, figure 8. 



"Depressed orbicular, rather thin, closely obliquely striate ; 

 :spire convexly conical, suture deeply impressed ; whorls 5 — 6, 

 very convex, the last considerably deflected at the aperture ; 

 .aperture lunate, the lip white, narrowly reflected and dilated 

 into and covering the umbilicus. Horn color, with more or 



