OF CONCHOLOGY. 



45 



12. Mesodon Mitchelliana, Lea. 



Plate 8, figure 10. 



Subglobose, moderately thick, translucent, finely striate ; 

 spire convexly conical, suture not deeply marked ; whorls 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 

 6, 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 mill. 



"Washington Springs, Arkansas. 



Distinguished by its depressed form. Although described 

 nearly twenty years ago, no other locality than that above 

 y-iven has been discovered. 



XX 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 



