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TRICHOTROPIDAE 167
is white in color (although the periostracum is yellow-brown), with more
prominent spiral threads, and with coarser spiral threads in the young. Found
offshore.
Hipponix barbatus Sowerby (Bearded Hoof-shell) from the same region
is limpet-shaped, with coarse, nodulated ribs which are largest on the anterior
slope of the shell. The edge of the shell is strongly serrated with cut lines.
The periostracum is very shaggy especially on the middle of the anterior slope.
Common.
Family VANIKOROIDAE
Genus Vanikoro Quoy and Gaimard 1832
Vanikoro oxychone Morch West Indian Vanikoro
Southeast Florida and the West Indies.
Vz inch in length, solid, strong and pure white. With 3 whorls. Charac-
terized by its large aperture, by its deep, narrow, arched umbilicus and
straight, rounded, pillar-like columella and by the 10 or 12 beaded, spiral
cords on the last whorl. Small axial threads tend to give a slightly cancellate
sculpture. Apex glassy and smooth. Suture well-indented. Uncommon in
shallow water.
Superjamily CALYPTRAEACEA
Faimly TRICHOTROPIDAE
Genus Trichotropis Broderip and Sby. 1829
Trichotropis borcalis Broderip and Sowerby Boreal Hairy-shell
Arctic Seas to Maine. Arctic Seas to British Columbia.
Plate 24d
V2 to % inch in length, with 4 to 5 carinate whorls. Shell not very
strong, chalky-white and covered with a thick, brownish periostracum which
has hairy spicules on the region of the shell's 3 major spiral cords. UmbiHcus
chink-like, bordered by a large, spiral cord. Spire usually eroded badly.
Numerous, crowded axial threads present. A common cold-water species
found from below low water to 90 fathoms.
Trichotropis cancellata Hinds Cancellate Hairy-shell
Bering Sea to Oregon.
Plate 24b
% to I inch in length, 5 to 6 rounded whorls bearing between sutures
4 to 5 strong spiral cords, between which there may be small axial ribs which
produce a cancellate sculpturing. Spire high, rather pointed. Aperture a little