Testa atro-purpurea, longitudinaliter subplicata, transverse, striata; anfractibus sex, ultimo supra carinato, plicis in medio evanescentibus, alteris medio carinatis; spira acuta; apertura angustata; cauda brevi. Length, .3; breadth, .15 in. (Mighels and Adams.)

Shell purplish-black, longitudinally subplicate, transversely striate; whorls six, the last carinated above and with evanescent median folds, the other whorls medially carinated; spire acute; aperture narrow; canal short. (Gould, Invertebrates of Massachusetts.)

Type locality. Casco Bay, Maine [Massachusetts, east coast of North America].
Distribution. Off Kinkazan in Miyagi Prefecture on Pacific coast, Noto Peninsula in Sea of Japan, both northwards to Bering and Chukchi Seas, circumpolar; 0-869 m [250-425 m].
Material examined. WA05-DE250D (le); WA06-DE280D (16+5e); WA06-DE350 (3+le); WA06-DE410 (le); WA06-EF425D (1+le); WA06-FG350D (le); WA07-C350D (6+14e); WA07-D310(3).
Remarks. Curtitoma violacea was originally described from the northwestern Atlantic, and has been shown to be widely distributed in the boreal-arctic northern hemisphere (Bogdanov, 1990). In Japanese waters, it has been recorded from off Nemuro in northeastern Hokkaido (Bog¬danov, 1990) and from the Noto Peninsula to Sado Island in the Sea of Japan (Bogdanov and Ito, 1992). Bogdanov (1990) showed a remarkably wide range of intraspecific variation in shell shape and sculpture in this species, and the specimens examined here fall within that range. They represent a range extension for this species southwards to the Pacific coast of northern Japan.

Distribution. Panarctic-circumpolar (Thorson 1941: 107); the species had already been recorded from W. of Ireland in 990 m (Massy, 1930: 323).
Remarks. O. violacea is quite variable both in sculpture and colour, from glassy white to ochraceous fawn. It is the only true Oenopota of the area with dominant spiral sculpture. It has a distinctly shouldered sinus without spiral lines, evenly curved inner lip and obtuse protoconch.
The nomenclature of the present species is most unfortunate. The first available name, bicahnata Couthouy, cannot be used because it is preoccupied by Murex bicarinatus W. Wood, 1828, transferred by Wood himself to Pleurotoma; it is a synonym of Tunis cryptorraphe Sowerby (Powell 1964: 335), and therefore a true Turris = Pleurotoma s.s. The next available name is Pleurotoma violacea Mighels & Adams. Johnson (1946: 230) selected as lectotype a shell in MCZ 165994, illustrated pi.27 fig. 5. That specimen, however, is a typical Oenopota tenuicostata. Strictly speaking the name violacea cannot be used for the species also known as bicarinata Couthouy, but should instead be used for the species O. tenuicostata. It would then be necessary to use the next available name, Defrancia becki Moller, 1842, which has merged long ago into the synonymy of bicarinata Couthouy and has not been used for a very long time. We understand that this would only increase the confusion in the genus and change the names of two of the better known species of
Oenopota. We have therefore decided to use the name violacea in the original sense of Mighels & Adams and to disregard the lectotype designation by Johnson. In any case, the systematics of Oenopota are in much too chaotic a condition for the question to be brought now to the International Commission on Zoological Nomenclature.

Type locality, Casco Bay, Maine.
RANGE. Sea Horse Islands, Arctic Ocean, to Bering Sea to Sitka, Alaska. Circumboreal. Fossil on Gravuna Island.