Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN MARINE MOLLUSKS. 25
tional cords, which equal those between the sutures in strength and
have about the same spacing. The spaces between these spiral cords
are about as wide as the cords. In addition to the spiral cords, the
whorls are marked by slender axial ribs, which are slightly pro-
tractive. Of these ribs, 12 occur upon the first, 16 upon the second
and 28 upon the last turn. The junctions of the axial ribs with the
spiral cords form slender tubercles, while the spaces enclosed between
them appear as well rounded, strongly impressed pits. On the
anterior half of the base, the axial riblets become much enfeebled, so
that here the pitting is less apparent. Sutures strongly constricted;
aperture moderately large, decidedly channeled posteriorly and anteriorly;
outer lip thin, showing the external sculpture within. The
inner edge of the columella and the parietal wall is covered with a
thin callus.
The type and two specimens of this species, Cat. No. 249730,
U.S.N.M., come from Port Alfred (Coll. No. 1002). The type has four
postnuclear whorls and measures: Length, 3.1 mm. ; diameter, 1 .4 mm.
MANGILIA CONSANGUINEA Sowerby.
Cat. No. 249747, U.S.N.M., contains one specimen from Port
Alfred (Coll. No. 1019). This species was described by Sowerby as
Columbella consanguinea, but we believe that it belongs to Mangilia.
MANGILIA NISGA, new species.
Plate 7, fig. 1.
Shell small, yellowish white. Nuclear whorls small, one and a half,
smooth, forming a very small, well-rounded, white apex. Postnuclear
whorls with a very strong sloping shoulder, which is bounded
anteriorly by a strong tuberculated spiral cord. In addition to this
cord, the whorls are marked by three additional cords, which decrease
in strength successively from the strong cord at the shoulder, to the
suture. The space between the strong shoulder and the summit of
the shell is marked by a strong spiral thread. Base of the last whorl
marked by a peripheral cord, about as strong as the one adjacent to
it posteriorly and two others as strong as this, having the same spac-
ing as those on the spire. The columella is provided with four cords,
of which the fourth, which marks the anterior limit of the columella,
is as strong as the first, while the two intermediate ones are less
strongly developed. In addition to the spiral sculpture, the whorls
are marked with rounded, low, quite regularly spaced, axial ribs,
of which 10 occur upon the first and second, and 14 upon the last
turn. These ribs render the spiral cords tuberculated at their junc-
tion with them. In addition, to these strong axial ribs, the entire
surface of the shell, between the sutures ami the anterior half of the