18 
essentially by tbe much more elevated spire, and by the superior 
half of the dilated lip being abruptly narrowed so as to form a 
prominent angle near the middle. It is also a much thicker shell. 
H. INTERNA.— Shell yellowish red ; volutions six or eight ; 
whorls with regular, equidistant, elevated, obtuse lines across 
them, separated by regular grooves ; lines obsolete beneath; spire 
convex, little elevated ; aperture very straight, tranverse, less 
than one half of the longitudinal diameter ; labrum not reflected ; 
within, upon the side of the labrum, two prominent, lamelliform 
teeth, of which the superior one is largest, and neither of them 
attains the edge of the lip ; region of the base of the columella 
much indented ; umbilicus obsolete or wanting. 
Transverse diameter more than three-tenths. Height of the 
columella about three- twentieths of an inch. Inhabits Lower Mis- 
souri. 
Of two specimens which I obtained, the larger one had six 
volutions, and the smaller one had eight ; the superior tooth in the 
larofer one was concave towards the base of the shell. It is a 
remarkable and very distinct species. 
H. CHERSiNA. — Shell subglobose-conic, pale yellowish white, 
pellucid, convex beneath ; volutions about six, wrinkles not dis- 
tinct ; spire convex-elevated ; suture moderate ; body whorl 
slightly carinated on the middle ; mouth nearly transverse, un- 
armed, the two extremities nearly equal ; labrum simple ; umbilicus 
none. 
Inhabits the Sea Islands of Georgia. Breadth one-tenth of an 
inch. Cabinet of the Academy. 
A very small species. But one specimen occurred in a cotton 
field. It is rather larger than H. lahyrinthica. 
H. GULARis. — Shell subglobose, pale yellowish horn color ; 
polished, pellucid, beneath near the aperture whitish-yellow opake ; 
volutions six or seven, with prominent, somewhat regular wrinkles ; 
spire convex, a little elevated ; suture moderate ; labrum not re- 
flected ; throat far within upon the side of the labrum, bidentate ; 
teeth lamelliform, of which one is oblique and placed near the 
middle, and the other less elongated, placed near the base ; um- 
bilicus none. 
Breadth more than one-fourth of an inch. Inhabits Ohio and 
Pennsylvania, 
