Shell small, rather thin, somewhat inflated, elliptical, inequilateral, strongly plicate on the posterior slope.

Epidermis dark yellow, smooth, polished, covered with dark green pencilled rays which tend to break into a net-work of angular lines covering the entire surface.

Anterior end compressed, rounded, and slightly elevated above the line of the hinge superiorly; posterior extremity obtusely rounded, the tip being nearly on the median line of the shell; posterior ridge somewhat angled; dorsal slope covered with strong sub-concentric, somewhat irregular ridges extending from the posterior ridge to the margin; basal margin regularly curved; hinge margin nearly straight, slightly angled between the cardinal and lateral teeth.

Habitat, Calvary, Ga. Only three specimens of this little species were received, and these, unfortunately, without any information as to the stream where they were found.

This species belongs to the "conradicus" group of Medionidus as defined by Simpson, and is most nearly related to M. penicillatus.