Description
Author: Jan Delsing
Text ID: 93949
Text Type: 1
Page: 0
Created: 2019-05-27 00:40:42 - User Delsing Jan
Language: EN
Text function: [[t:1159854,textblock=93949,elang=EN;Description]]
Shell small to medium sized, 8-16 mm. narrowly biconic-fusiform, with a tall tabulated spire, and a long narrow body-whorl, slowly tapered to a short very shallowly notched anterior canal. Protoconch small, turbinate, of about 2,5 whorls, tip small, smooth and flattened, next whorl smooth also, but becoming weakly subcarinate; final whorl conspicuously bicarinate, crossed by fine axial threads. Adult whorls tabulated by a flat almost horizontal shoulder. Strong vertical axial folds extend from the shoulder angle to the lower suture and over the body-whorl to the neck. The axials are also continued weakly over the shoulder slope to the upper suture. Spiral sculpture of closely spaced cords extends from the suture to the anterior end but these are usually much weaker on the shoulder slope. Aperture rather long and narrow; outer lip thin edged. Sinus a shallow concavity, its apex at about the middle of the shoulder slope. Operculum approaching vestigial, very narrowly ovate, subquadrate, with a terminal nucleus. Radula consisting of bundles of twisted rods.
Bartsch's Turritomella (=Turritoma) is not worth recognition since its only stated differen-tiating character is that the spiral cords are supposed to be weaker over the shoulder slope as opposed to being evenly cordate over the whole shell in Propebela. Actually the strength of the shoulder spirals is variable, for some examples of turricula have an almost smooth shoulder. The periostracum is either exceedingly thin or absent. Range — Recent, circum-Arctic, off Japan in 167 fathoms, and off California in 580-870 fathoms, Pleistocene of England and Iceland, Pliocene of Japan.
Powell, 1966.The Molluscan Families Speightiidae and Turridae. (Secundary description)