Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN MARINE MOLLUSKS. 19
CLAVATULA HALIPLEX, new species.
Plate 2, fig. 3.
Shell robust, fusiform. Whorls sloping from the summit and the
periphery to a depressed line midway between the sutures. The
portion posterior to the median line is smooth excepting the strongly
retractive lines of growth and spiral striations. The portion anterior
to it is marked by distant, low, broad, feebly developed axial ribs,
which appear as nodules above the sulcus. On this part the incremental
lines are decidedly protractive. Sutures well marked. Pos-
terior portion of base well rounded, anterior part produced rendering
the left outline of the whorl concave, marked by feeble extensions
of the ribs which disappear shortly after passing over the periphery.
Entire surface of spire and base marked by very fine, closely spaced
wavy spiral striations. Aperture of irregular outline; posterior angle
acute; sinus moderately deep, in the middle between the periphery
and summit; columella stout, somewhat sinuous and twisted, cov-
ered by a thin callus, which also extends over the parietal wall.
Color uniformly cream yellow. In some of the young specimens the
space between the sulcus and summit and tip of base are white, the
rest light brown.
The type and one other individual, Cat. No. 186992, U.S.N.M.,
come from Port Alfred (Coll. No. 524). The type has lost its early
whorls, the seven remaining measure: Length, 29.5 mm.; diameter,
11.6 mm. Cat. No. 186997, U.S.N.M., contains three young indi-
viduals from the same locality (Coll. No. 529).
CLAVATULA HALISTREPTA, new species.
Plate 2, fig. 5.
Shell fusiform. Whorls marked by a narrow, obscurely nodulous
spiral keel at the summit, which is followed by a depressed spiral
sulcus that equals the keel in width, the two comprising the posterior
two-fifths of the whorls between the sutures. Anterior three-fifths
marked by strong, broad, low, rounded, slightly protractive axial
ribs, which are strongest at their junction with the sulcus, beyond
which they scarcely extend. The type has lost the early whorls;
upon the first of those remaining there are 10 and upon the rest, 12
ribs. Intercostal spaces about one-half as wide as the ribs. On
account of the closely appressed summits, the sutures are poorly
defined. Base of the last whorl moderately long, marked by the con-
tinuations of the ribs, which gradually weaken in strength as they pass
forward. Entire surface of the spire and base marked by lines of
growth and numerous, closely crowded, fine, wavy, spiral striations.
Posterior angle of aperture acute, sinus below the keel at the summit;
columella sigmoid, covered by a thin callus which also extends over