interna = internal [latin]
Shell yellowish-red; volutions six or eight; whorls with regular, equidistant, elevated, obtuse lines across them seperated by regular grooves; lines obsolete beneath; spire convex, little elevated; aperture very strait, transverse les than one half of the longitudunal 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 attain the edge of the lip; region of the base of the columella much indented; umbilicus onsolete or wanting.
Transverse diameter more than 3-10.
Height of the columella above 3-20.
Inhabits Lower Missouri
Of the two specimens which I obtained, the larger one had six volutions, and the smaller one had eight; the base of the shell. It is a remarkable and very distinct species.
Original Description Citation:
Say, T. (1821). Description of univalve shells of the United States. Journal of the Academy of Natural Sciences of Philadelphia. 2(1): 149-179.
Nature Serve Conservation Status: