246 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Seguenzia certoma Dali, 1919 
Proceedings of the United States National Museum, 56:343. 
Shell small, trochiform, white, with a minute, smooth globular nucleus 
and seven subsequent strongly sculptured whorls; suture obscure; spiral 
sculpture of a small, closely beaded thread at the summit of the whorl, 
separated from a low, sharp carina by a wider, excavated interspace, and 
the latter from a more prominent peripheral carina by a still wider space; 
on the base are three sharp threads followed by three lower rounded 
threads, which approach the pillar; axial sculpture of fine, even, arcuate 
wrinkles, which, except where they bead the posterior thread, are chiefly 
visible in the interspaces; the suture is laid on the peripheral thread, and 
between it and the outer lip at the aperture is a very deep sulcus; the outer 
lip is much produced and its edge is modified by the external sculpture, 
so that there is a sulcus at the end of the peripheral keel, another at the 
middle of the base, and still another at the base of the pillar, which is 
arcuate and produced like a small plait; the base is imperforate, the body 
with no visible glaze. Height, 5; diameter, 3.5 mm. (Dali.) 
Type in United States National Museum, No. 211167. Type locality, 
U.S. Fish Commission Station 4337, off Point Loma, California, in 565 to 
680 fathoms. 
Range. Known only from type locality. 
Family TRIFORIDAE 
Genus TRIFORA (Deshayes) Blainville, 1828 (Triphonis) 
Shell turreted, sinistral; aperture round, produced anteriorly into a 
closed, tubular canal, sometimes with a posterior, closed canal. (H. & A. 
Adams.) 
Type. Trifora perversa Linnaeus. 
Distribution. Straits of Malacca, Australia, New Guinea, New Ire¬ 
land, West Indies, Mediterranean, Pacific and Atlantic coasts of America. 
Fossil, Eocene, Norway, Australia; Pleistocene, San Pedro. 
Trifora peninsularis Bartsch, 1907 
Plate 71, fig. 2 
Proceedings of the United States National Museum, 33:255; PI. 16, fig. 2. 
Shell sinistral, small, broadly elongate, conic, dark brown. Nuclear 
whorls four, light brown, increasing regularly in size, provided with spiral 
and axial sculpture (but this is too badly worn to be properly diagnosed 
in all our specimens). Post-nuclear whorls eight, separated by channeled 
sutures. The first four post-nuclear whorls have a double spiral row of 
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