Cryptogemma polycaste Dall, 1919 (basionym) Carinoturris polycaste is a species of sea snail, a marine gastropod mollusk in the family Pseudomelatomidae, the turrids and allies.

(Original description) The white shell has a pale olivaceous periostracum.

These are rather slender and moderately rounded except for a single strong peripheral keel which marks the deepest part of the anal sulcus.

The suture is distinct, not appressed, with a feebly indicated flattish area between it and the posterior edge of the anal fasciole, which between the keel and the flattening is slightly impressed.

[2] This marine species was found off Tillamook Bay, Oregon, USA.