Pilsbry’s (1917) description of his genus is follows: “the shell is umbilicate pyramidal, light-colored and spirally striate, last whorl scarcely peristome broadly expanded but thin, shortly adnate above. No angular 0-3 plicae in the lip.” Pilsbry further states, “This group is peculiar for having lost the angular lamella, leaving a simple parietal. Except in [A.] messageri, the other teeth are more or less completely degenerate. This group is related to Hypselostoma by the spiral sculpture but differs by having no angular lamella, and the last whorl is adnate. This last is not a very important difference, and one which may perhaps disappear with future discoveries.”