Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN MARINE MOLLUSKS. 27
the rest of the turn between the sutures; of the latter 3 occur upon
the first to third, 4 upon the fourth, 7 upon the fifth and sixth, 1 1 upon
the next, and 13 on the last turn. The spaces between tho spiral
threads about equal the spiral threads in strength. The surfaco
between the spiral threads is covered with fine granulations on the
spire. The last whorl anterior to the periphery is marked by 27 spiral
cords, which are about equal and equally spaced, being only a trifle
stronger on the columella. Sutures well constricted; aperture with
a strong deep sinus at its posterior angle, which renders the outer lip,
anterior to this, decidedly claw-like; outer lip strongly reenforced
within by a callus which bears about 15 denticulations on the inner
surface. Columella and parietal wall glazed with a thin callus.
The type, Cat. No. 210, U.S.N.M., was collected by William
Stimpson on the North Pacific Exploring Expedition at False Bay.
It has nine post-nuclear whorls and measures : Length, 15.3 mm. ; diameter,
5.7 mm. Tho specimen was labeled Clathurella gracilis Montagu.
It differs from this in being uniformly smaller and having ever so
many more spiral cords. Named for Dr. Marcus Benjamin of the
United States National Museum.
MANGILIA? CRASSILIRATA Smith.
Cat. No. 187006, U.S.N.M., one specimen from Port Alfred (Coll.
No. 538). Cat. No. 250459, U.S.N.M., contains another specimen
from the same place (Coll. No. 1332).
MANGILIA ARATA, new species.
Plate 3, fig. 8.
Shell vinaceous cinnamon. Nuclear whorls two, dextral, smooth,
well rounded. Post-nuclear whorls with the posterior third between the
sutures forming sloping shoulders, the rest well rounded, ornamented
by strong, rounded, almost vertical, axial ribs, which are about one-half
as wide as the intercostal spaces. Ten of these ribs occur upon the first
and second, 12 upon the third, and 14 upon the penultimate turn. In
addition to the ribs the whorls are marked by strongly raised, narrow,
spiral bands, of which, four, equally strong and equally spaced, divido
the space between the suture and the shoulder and three, that between
the shoulder and the summit; of these, two are close together, immediately
posterior to the shoulder, while the third divides the space
between them and the summit. Sutures somewhat constricted.
Periphery of the last whorl well rounded. Posterior half of base well
rounded and marked by the continuations of the axial ribs. Ante-
rior half produced. Entire base crossed by 20 raised spiral bands,
the posterior of which equals those on the spire, while thoso on the
anterior extremity appear as rounded lirations. Aperture of irregu-
lar outline, channel strong and deep, separated from the parietal wall