Cadulus colubridens R. B. Watson, 1879 Siphonodentalium colubridens is a tusk shell or scaphopod in the family Gadilidae of the order Dentaliida.

[1] This species was described from only one specimen collected in 1874 by the H.M.S.

[2] The original description and a drawing was published in 1879 by Robert Boog Watson, a Scottish malacologist who reported on the Scaphopoda and Gastropoda of the Challenger expedition.

The specimen was collected at a depth of about 1300 m in ocean waters east of North Island, New Zealand.

The species is described as having a smooth, white shell, with a swelling below the anterior aperture and a length of 15 mm.