Bulletin - United States National Museum - Smithsonian Institution

170 BULLETIN 91, UNITED STATES NATIONAL MUSEUM.
equally strong is about as far within the umbilicus as it is separated
from the first of the five additional spiral cords which mark the inner
umbilical wall. The space between the outer limiting cord and the
periphery is marked by fine spiral lirations, equaling those on the
spire in strength and spacing. Aperture subcircular; outer lip thin,
showing the external sculpture within ; inner lip strongly curved and
slightly reflected.
The type, Cat. No. 250556, U.S.N.M., comes from Port Alfred
(Coll. No. 1429). It has one and one-third postnu clear turns, and
measures: Altitude, 1 mm.; greater diameter, 1.5 mm.
CYCLOSTREMELLA AFRICANA, new species.
Plate 29, figs. 1, 2, 3.
Shell purplish pink, obscurely dotted and flecked with white excepting
the nuclear whorls, which are of yellowish horn color. Nuclear
whorls two and one-half, smooth, forming a depressed helicoid spire.
Postnuclear whorls well rounded, appressed at the summit, marked
by many equal, and subequally spaced, fine, spiral lines which are
about one-fourth as wide as the spaces that separate them. In
addition to the spiral sculpture, the whorls are marked by fine lines
of growth and irregularly distributed, strong, depressed lines which
appear as feeble varicial markings. Sutures well marked. Periphery
of the last whorl rounded. Base well rounded, very broadly, openly
umbilicated, marked like the spire by fine, incised spiral lines and the
axial sculpture, the strong impressed axial lines becoming accentu-
ated at the umbilicus, rendering the outer umbilical edge strongly
notched. Aperture subcircular; posterior angle slightly channeled;
outer lip joining the basal lip in a strong, even curve; inner lip
moderately thick, slightly revolute; parietal wall covered with a thick
callus which is so developed as to give the aperture the appearance
of being notched at this place.
The type and another specimen of this species, Cat. No. 187101,
U.S.N .M., come from Port Alfred (Coll. No. 645). The type has a
little more than one and one-half postnuclear whorls, and measures:
Altitude, 1.7 mm.; greater diameter, 2.1 mm.
CAPORBIS, new genus.
Shell very small, sinistral, planorboid, marked with numerous
lamellar, closely spaced, axial ribs.
Type.— Caporbis africana.
CAPORBIS AFRICANA, new species.
Plate 35, figs. 1, 2, 3.
Shell planorboid, sinistral, very small, bluish white, semitrans-
lucent. Early whorls completely covered by the succeeding turns
on the upper surface, where the last turn only is visible. This is
marked by strong lamellar ribs which are decidedly sinuous and have