Gemmula sibukoensis: Adult shell 41 to 48 mm. (about 2 inches) in height. Fusiform, with a tall spire, about 1 1/5 times height of aperture, plus canal. Whorls 10. plus a small polygyrate conic protoconch of 3 whorls or more, the last, at least, axially costate. Protoconch eroded and the tip missing in all available specimens. Spire whorls turreted by a strong rather broadly rounded peripheral sinus-rib, which is set low on the whorls, almost at the lower suture, hut with a narrow space beneath it. which allows the emergence, over the last few whorls, of the uppermost basal spiral. Peripheral sinus-rib densely sculptured with laterally com-pressed, concavely arcuate axials, 27 to 31 per whorl, overridden by 2, occasionally 3, weak spirals. Spiral sculpture consisting of rather strong but narrow cords, 3 to 5 on the wide, steeply descending shoulder and 16 to 18 on the base; 3 on the upper part of the base rather stronger than the rest, which diminish in size gradually to the end of the anterior canal. Labial sinus of moderate depth, V to U-shaped, its apex wider than the crest of the sinus-rib. Colour creamy white. Surface crossed by dense sharp axial growth lines.
Range—Borneo, Moluccas and Philippines. 50 to 484 fathoms.
Remarks — This is another member of the group with the peripheral carina set low down on the spire whorls. It appears nearest to sibogae Schepman, hut differs in having a heavier peripheral carina a little above the lower suture, allowing the emergence of the uppermost basal spiral over the later whorls, and the shape of the body whorl, which is but slowly contracted over the base to a shorter and flexed, not straight canal.