See text Pleurotomariidae, common name the "slit snails", is a family of large marine gastropods in the superfamily Pleurotomarioidea of the subclass Vetigastropoda.

The first living specimens of a species in this family, Perotrochus quoyanus, were dredged in 1879 in deep water off the West Indies by the "Blake" expedition of William Healey Dall.

It is umbilicate or imperforate, having a deep slit or sinus in the outer superior margin of the peristome, which serves the purpose of an exhalant phase of respiration., and leaves on the corresponding part of the whorls a peculiarly sculptured band, the "anal fasciole" or the "slit fasciole."

The broad epipodium (the lateral grooves between foot and mantle) is thin, entire, and fringed with a row of small, short papillae.

After taking a considerable hit during the Cretaceous–Paleogene extinction event, they have been restricted to deeper waters through the Cenozoic.

[5] Species in the family Pleurotomariidae live at depths of 150–300 m as benthos on the bottom in the mesopelagic zone.

They are preyed upon by crustacea and fish, but are remarkably resistant to attack — they secrete a white fluid when endangered, thought to repel predators.