hitmewithyourmesomphix's Identifications

5 mm greater diameter
Depressed heliciform with angular to carnate periphery
4.5 moderately coiled whorls
Widely umbilicate
Simple lip
No teeth
Rib like transverse striae
Pretty sure the genus is Discus, no so sure on the species.
D. whitneyi is most likely, but angular periphery does not match.
D. nigrimontanus is possible, but this sample is not as depressed as I would expect, and it is rare in KY, being only found in the far west of the state.
Ruled out D. patulus due to lack of callous tooth and the angular periphery.
Ruled out D. catskillensis as it is presumed extinct in KY.

This is my best guess on these, though these four shells do not quite match in terms of diameter and height, and number of whorls. Also, there is only a slight callus at a point internal to the aperture, which appears to be different than the feature described for this species.

Found in leaf litter near limestone ledges and cliffs, or in limestone boulders, on forested mountain slopes.

ID is based on info from Daniel Dourson's book "Kentucky's Land Snails", and images here, but I am open to suggestions and alternate IDs!:

http://www.carnegiemnh.org/science/mollusks/va_imagegallery.html