Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFEICAN JUAEINE MOLLUSKS. 127
Two additional lots, both from Port Alfred, are in the collection of
the United States National Museum. Cat. No. 250416, one specimen
(Coll. No. 1289), the other Cat. No. 250417, one specimen (Coll. No.
1290).
AMPHITHALAMUS AFRICANUS, new species.
Plate 21, fig. 6.
Shell minute, elongate-conic, semitransparent. Nuclear whorls one
and a half, well rounded, smooth. Postnuclear whorls almost three,
strongly* rounded, appressed at the summit, marked by numerous,
regular, fine, decidedly retractive axial riblets, the spaces between
which are about one and a half times as wide as the riblets. Sutures
strongly constricted. Periphery of the last whorl well rounded.
Base somewhat produced, marked like the spire by the continuations
of the riblets. Aperture broadly oval, decidedly oblique; outer lip
thin; inner lip strongly curved at some little distance from the parie-
tal wall. The space between the inner edge of the outer lip and the
parietal wall form a shelf, as is usual in Amphithalamus .
The type, Cat. No. 250415. U.S.N.M., comes from Port Alfred
(Coll. No. 1288). It measures: Length, 1.2 mm.; diameter, 0.5 mm.
Genus ALVANIA Risso.
ALVANIA NEMO, new species.
Plate 5, fig. 3.
Shell small, elongate-ovate, yellowish white. Nuclear whorls one
and one-half, well rounded, smooth. Postnuclear whorls inflated,
strongly rounded, marked between the sutures by very regular, well
developed, evenly spaced spiral cords, of which four occur upon the
second and third, and 6 upon the penultimate turn. The space between
the appressed summit and the first spiral cord is a little wider
than those between the other cords. In addition to the spiral cords
the whorls are marked by feeble incremental lines. Periphery of the
last whorl inflated. Base moderately long, well rounded, narrowly
umbilicated, marked with two, feeble, spiral cords and fine, incremental
lines. Aperture broadly oval; posterior angle obtuse; outer lip thin,
showing the external sculpture within; columella strongly curved,
free, partly reflected over the umbilicus; parietal wall glazed with a
thin callus.
The type, Cat. No. 187057a, U.S.N.M., comes from Port Alfred
(Coll. No. 595). It has almost four postnuclear whorls, and measures:
Length, 1.8 mm.; diameter, 1 mm.
The following four additional lots from Port Alfred are in the col-
lection of- the United States National Museum. Cat. No. 250403,
two specimens (Coll. No. 1276). Cat. No. 250402, two specimens.