254 AMERICAN JOURNAL 



GASTRODONTINtE. 



Genera. 

 * Not dentate. 



1. Mesomphix, Eafinesque. Shell moderate in size, um- 



bilicate or perforate ; aperture obliquely semihmar. 



2. CoNULUS, Fitzinger. Shell minutely conical, imperfo- 



rate or perforate; aperture depressed transverse, its 

 lower margin extending to the basal axis of the shell. 



** Lamcllarhj dentate. 

 f Outer whorl dentate. 



3. Gastrodonta, Albers. Shell minute, with one or more 



laminte revolving within the base. Surface nearly 

 smooth, polished. 



f f Outer whorl and columella hath dentate. 



4. Strobi LA, Morse. Shell minute, Avith laminre both on 



the base and the columella. Surface strongly striate. 



MESOMPHIX, Raf. 



a. Diam. == 10 — 15 mill. 



1. Mesomphix iiitertexta, Binney. 



Plate 4, figure 33. 



Subglobose, whorls 6 — 7, closely striated, sometimes with 

 very faint revolving lines, yellowish horn color, slightly 

 angled, and sometimes with a light and beneath it an ill-de- 

 fined brown 'band at the periphery. Very convex below. 

 Aperture obMque, narrow lunate, base of shell thickened by 

 a calcareous deposit within ; umbilicus small. 



Diam. 19 mill. 



Western New York to Georgia, and westward to Missouri 

 and Iowa. 



Larger than the next, and not quite so conical; the slightly 

 angled periphery and bands of color, when ])resent, offer dis- 

 tinctive characters. The shell is also thicker and not so pel- 

 lucid, and frequently exhibits spiral lines, not visible on lUjcra. 



