Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN MARINE MOLLUSKS. Ill
addition to the above sculpture, the spire is marked by exceedingly
fine lines of growth and microscopic spiral striations. Sutures
channeled. Periphery of the last whorl marked by a spiral sulcus
as broad as the one posterior to the suprasutural cord and, like that,
crossed by the axial ribs, which terminate at its posterior margin.
Base short, marked by two spiral cords which are of equal strength
and confined to the posterior half of the base. The anterior half of
the base between the last cord and the insertion of the columella is
slightly concave in the adolescent shell. Aperture subquadrate,
decidedly channeled anteriorly; posterior angle obtuse; outer lip
rendered sinuous by the sculpture; columella stout; parietal wall
glazed with a thin callus.
The type and another specimen, Cat. No. 250354, U.S.N.M., come
from Port Alfred (Coll. No. 1227). The t}^pe, which is an adolescent
specimen, has eight and a half postnuclear whorls and measures:
Length, 4.5 mm.; diameter. 1.5 mm. Cat. No. 250357, U.S.N.M.,
contains another specimen from the same locality (Coll. No. 1230).
CERITHIOPSIS (CERITHIOPSIS) NINA, new species.
Plate 12, fig. 2.
Shell very small, light chestnut brown. Nuclear whorls smooth,
forming the slender, mucronate apex of the shell. Postnuclear whorls
slightly shouldered at the summit, moderately rounded, marked by
three spiral cords, of which the first is at the summit, the third about
as far posterior to the suture as it is separated from its neighbor posteriorly.
In addition to the spiral sculpture, the whorls are marked
by strong axial ribs which equal the spiral sculpture in strength.
The junctions of the axial ribs and the spiral cords form tubercules,
while the spaces inclosed between them form well impressed, squarish
pits. The tubercles of the cord at the summit are slightly truncated
posteriorly, and slope gently anteriorly; those of the succeeding two
cords are abruptly truncated posteriorly, sloping gently anteriorly.
Of the axial ribs, 18 occur upon all the whorls except the penultimate,
on which there are 20. Sutures moderately constricted.
Periphery of the last whorl marked b} r a strong spiral cord, the space
between it and the suprasutural cord being crossed by the continua-
tion of the axial. ribs which terminate at the posterior edge of the
peripheral cord. Base slightly concave, with a spiral cord at the
insertion of the columella. Aperture strongly channeled anteriorly,
almost circular; outer lip thin; columella covered with a thick callus
which is reflected over the parietal wall and connects this with the
posterior angle of the aperture, rendering the peristome complete.
The type and another specimen, Cat. No. 250358, U.S.N.M., come
from Port Alfred (Coll. No. 1231). The type has almost five postnuclear
whorls, and measures: Length, 1.9 mm.; diameter, 0.7 mm.