Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN- MARINE MOLLUSKS. 147
threads which are about as wide as the spaces that separate them.
Postnuclear whorls marked by four, strong, broad, rounded, spiral
cords of which the first is at the summit, while the second is a little
nearer the first than it is to the third, the fourth, marking the periphery,
is about as far from the third as that is from the second. On
the last turn two additional slender spiral threads make their appear-
ance, one immediately anterior to the second, the other, anterior to the
third heavy spiral cord. The cords are marked quite regularly by
weak tubercles which are about as long as they are broad and are
separated from each other by a space about two-thirds as wide as a
tubercle. Sutures deeply channelled. Periphery of the last whorl
well rounded. Base short, well rounded, marked by seven strong
rounded spiral cords which increase in size from the periphery to the
columellar chink. The spaces separating the cords are deep sulci
narrower than the cords. The entire surface is marked by closely
spaced, very slender, wavy, axial threads. Aperture very oblique,
small, outer lip bending strongly anteriorly to join the columella,
thin at the edge, where it is rendered wavy by the sculpture, but very
thick a little behind the edge; columella short, decidedly revolute;
parietal wall covered with a thick callus which completes the peri-
treme.
Cat. No. 24269, U.S.N.M., contains Gould's cotypes, three specimens
collected by William Stimpson on the North Pacific Exploring
Expedition at Simons Bay, Cape of Good Hope. We have figured
the largest of these, which has two and one-fourth postnuclear whorls,
and measures: Altitude, 5.5 mm.; greater diameter, 6.5 mm.; lesser
diameter, 6.0 mm.
LEPTOTHYRA AFRICANA, new species.
Plate 22, figs. 1, 2, 3.
Shell with moderately elevated spire. Nuclear whorls white, the
rest marked with irregular axial bands of white and reddish brown.
Nuclear whorls two, apparently smooth. Postnuclear whorls marked
the first of which
with three strong spiral cords between the sutures ;
is a little below the summit, while the third is a little posterior to the
periphery, the second being midway between them. The sulci
between the cords are almost two times as wide as the cords. On the
last whorl an additional cord appears between the first and second
and second and third. In each case this anterior cord is greater than
the primary ones and a little nearer to the one posterior than to its
anterior neighbor. In addition to the spiral sculpture, the whorls
are marked by numerous, fine, retractive, axial threads. Sutures
strongly impressed. Periphery of the last whorl marked by a strong
spiral cord. Base short, well rounded, marked with four strong,
spiral cords which equal the peripheral one in strength and a tumid