MESODON. 



335 



Mesodon Downieana, I'land. 



Shell uiubilicatc, umbilicus nearly covered, subglobose, thin, subpellucid, 

 with obsolete rib-like stria;, decussated with crowded microscopic spiral lines, 

 greenish horn-colored ; spire short, obtuse ; whorls 5, convex, the 

 last tumid, anteriorly somewhat gibbous, scarcely descending, 

 constricted ; aperture obli(j[ue, lunate oval ; peristome white, laljl- 

 ate, reflected, right margin expanded, columellar margin angu- 

 larly dilated, nearly covering the umbilicus. Greater diameter 

 10^, lesser 9| mill. ; height, 6 mill. 



Fig. 217. 



M. Downieana. 



Fig. 218. 



Helix Dowiikana, Bland, Ann. N. Y. Lye, VII. 420, PI. IV. Figs. 

 23, 24 (1861). — W. G. Binney, L. & Fr.-W. Sh., I. 151 (1869). 

 Mesodon Downieana, TiiYON, Am. Joum. Conch., III. 47 (1867). 



Munroe County ; University Place, Franklin County ; Tennessee, Whitley 

 County, Kentucky. A species of the Cumberland Subregion. 



Animal with the usual characters of the genus. 



Jaw as usual ; over 10 ribs. 



The lingual membrane (PI. VIII. Fig. F) has 35—1—35 teeth, with 12 

 laterals. The side cusps and cutting points are visible on the second lateral 

 tooth. ' • 



Mesodon La^vi, Lewis. 



Shell narrowly umbilicated, globose, surface hardly broken by delicate in- 

 cremental stria;, horn-colored ; spire elevated, apex obtuse . 

 whorls 4, convex, suture impressed, the last globose, descending, 

 deeply constricted behind the peristome; aperture oblique, lu- 

 nate, narrow, with a linguiform tooth on the parietal wall ; peri- 

 stome white, thickened, reflected, its terminations approached 

 slightly, that of the columellar somewhat concealing the very 

 narrow umbilicus. Greater diameter 6, lesser 5 mill.; height, 3 

 mill. 



M. Lawi. Helix Lawi, Lewis, Proc. Acad. Nat. Sci. Philad., 1874, 118 



(Fig.). 

 Probably a species of the Cumberland Subregion. Thus far only found at 

 Hayesville, Clay County, North Carolina, in a field, at the roots of Strawberry 

 plants, by Miss Annie M. Law. 

 Animal unobserved. 



Mesodon jejuna, Say. 



Vol. in. PI. Xm. Fig. 2. 



Shell umbilicated, subglobose; epidermis corneous, nearly smooth; spire 

 rather prominent ; suture impressed ; whorls rather more than 5, the last am- 

 ple ; stria; of increase hardly visible ; peristome white, very narrow, reflected, 



