A fresh-water shell, closely allied to the Neritina; it generally has
the appearance of porcelain.
Shell ovate oblong, covered with epidermis, shaped like a Patella,
summit not spiral, but straight, turned quite to the base, and concave
beneath; no columella; the columellar edge replaced by a kind of sharp
partition, which covers part of the aperture, with a sinus at its left
extremity; muscular impression shaped like a horseshoe, open in front
and interrupted behind; thin, calcareous operculum, with a subulate,
lateral tooth adhering to the posterior margin; the other edges sharp.
Navicella elliptica.
N. lineata.
N. tessellata.
_N. elliptica._ The oval Navicella.
Shell covered with olive epidermis, under which it is smooth, shining,
spotted and streaked with purple, blue, or brown; spire curved,
prominent, extending beyond the margin.