They are aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails.

In other words what Pilsbry describes as the "impressed and turned in" apex of the shell is actually the center of the umbilicus.

The shell is minute, subdiscoidal, nearly flat above, convex below, perforate, carinate at the periphery, composed of about two rapidly enlarging whorls, the apex impressed and turned in.

Peristome thin, not continuous, the columellar margin straight and broadly dilated, somewhat thickened within.

The radula is not materially unlike that of Amphigyra, but the conchological features of the two groups are quite diverse, Amphigyra being Crepiduloid with a distinct "deck" or columellar plate, while Neoplanorbis is Planorbis-shaped, perforate, with a carinate periphery and no "deck."