Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN MARINE MOLLUSKS. 173
at the summit and the fourth is somewhat flattened, while that of
the rest is evenly rounded. Base openly umbilicated; umbilicus
occupying about one-third of the width of the base; bounded by a
very slender spiral cord. The space from the base of the ruffle to
this cord is evenly well rounded. The entire surface of the base is
marked by rather strong lines of growth and microscopic spiral
striations. This sculpture extends also into the umbilicus. Aper-
ture very oblique, irregularly triangular; posterior angle acute; outer
lip rendered denticulated by the external sculpture; inner lip slender,
strongly sigmoid, and slightly reflected.
The type, Cat. No. 250561, U.S.N .M., comes from Port Alfred
(Coll. No. 1434). Its greatest diameter is 2.3 mm.
DISCOPSIS TURTONI, new species.
Plate 33, figs. 1, 2, 3.
Shell small, discoidal, semitranslucent, bluish white. Nuclear
whorls one and one-half, smooth, well rounded, forming a depressed
helicoid spire with strongly impressed sutures. Postnuclear whorls
two and one-fifth, broad, well-rounded, with strongly impressed
sutures marked on the upper surface by rather strong, decidedly,
retractively curved lines of growth. Periphery of the last whorl
acutely keeled. Base very widely, openly umbilicated, there being
scarcely any external limit to the umbilicus, all the whorls showing
within. A slender spiral cord encircles the base about one-fourth
of the distance anterior to the periphery. On the base the lines of
growth assume a thread-like appearance, becoming stronger within
the umbilicus. The entire base is marked by microscopic spiral
striations. Aperture very oblique, of irregular outline; outer lip
thin, sinuous, showing the external markings within; inner lip de-
cidedly flexuose, thin.
The type and another specimen, Cat. No. 249766, U.S.N.M., come
from Port Alfred (Coll. No. 1038). The type measures: Greatest
diameter, 2.5 mm.; lesser diameter, 1.7 mm.
Genus LEPTOGYRA Bush.
LEPTOGYRA AFRICANA, new species.
Plate 36, figs. 4, 5, 6.
Shell very minute, semitranslucent, bluish white. Nuclear whorls
two, well rounded, smooth, forming a depressed helicoid spire. Postnuclear
whorls well rounded, marked by numerous fine, equal and
equally spaced, incised spiral striations of which about 35 occur between
the summit and the well-rounded periphery of the last whorl. The
axial sculpture consists of fine lines of growth only. Base strongly
rounded, somewhat inflated, with a moderately broad umbilicus
marked by the continuation of the fine lines of growth, which grow a
little stronger as they approach the umbilicus, and on the posterior