In gastropods, the direction of coiling in which, with the shell held upright (apex at the top), the APERTURAL opening is at the left; and in which, with the shell viewed from above the APEX, the coiling proceeds from the apex in a counterclockwise direction; = LEFT HANDED; opposite of DEXTRAL; See also:
See other gastropod shapes.
Illustration: Physella sp.; Photo: Busycon contrarium (Conrad, 1840)
Sinistral Shells - by design or accident