The shell is narrowly umbilicate, conic, a little obtuse at the apex, corneous, nearly smooth. The whorls are very convex, separated by a deep suture, the last whorl tubular. The aperture is distinctly oblique, almost circular, the upper end rounded, but a trifle more narrowly so than the base. It projects but little beyond the preceding whorl laterally. The peristome is thin, continuous, scarcely or barely in contact with the preceding whorl above.
Length 3.1, diam. 1.9, length aperture 1.1 mm.; 5 whorls (type).
Length 2.8, diam. 1.6, length aperture 0.85 mm.
Operculum having the spiral rather large, the nucleus being above the lower third.
This little species resemblesLyogyrusby its tubular whorls of small calibre. The whorls are more convex and increase less rapidly than inAmnicola walkeriana, which is also less slender.A. schrockingeriFfld. has less deeply convex whorls, and the apex is more acute.A. bakerianais much larger, with a more obtuse apex.
Found in Short Point Bay, Oneida Lake, near shore, in 3 feet of water, bottom of sand with algae; also in Lower South Bay, etc. Collected by Mr. F. C. Baker.
It is named for Dr. John M. Clarke, the distinguished Director of the Museum of the State of New York.