Bulletin - United States National Museum - Smithsonian Institution

124 BULLETIN 91, UNITED STATES NATIONAL MUSEUM.
of the succeeding turns slightly rounded, ornamented with five
nodulose spiral cords, of which the first, at the summit, and the last,
at the periphery, are the widest, the three intermediate ones being
of about equal width. The spaces separating these spiral cords
are strongly incised, narrow channels. In addition to the spiral
cords, the whorls are marked by low, retractive, axial ribs, of which
67 occur upon the last turn. The junction of the axial ribs and the
spiral cords, form low, rounded, elongated tubercles, the long axis
of which corresponds with the axial sculpture. Base moderately
rounded, marked with low spiral cords, of which the two adjacent
to the umbilicus are about doubly as wide as the rest; the one
bordering the umbilicus renders the edge of this crenulated. In
addition to these spiral cords the base is marked by the continuation
of the axial ribs, the junction of which, with the spiral cords, renders
these nodulose. The nodules, on the two cords near the umbilicus
are elongate, having the long axis parallel with the spiral sculpture,
while those on the rest of the cords are more or less rounded. There
is a deep sinus between the peripheral cord and the basal cord, fully
twice as wide as any of the sulci on the rest of the spire. Two slender
spiral threads are present in the sulcus. The parietal wall of the
umbilicus is marked with two moderately strong spiral cords. Aper-
ture subcircular, rendered somewhat sinuous by the external sculp-
ture; columella very stout, provided with two low, rounded, spiral
cords which divide it into two equal parts.
The type and another specimen, Cat. No. 249757, U.S.N.M., come
from Port Alfred (Coll. No. 1029). The type has almost four post-
nuclear whorls and measures: Greatest diameter, 9.6 mm.; lesser
diameter, 9 mm.; altitude, 4.6 mm. Cat. No. 186824, U.S.N.M.,
contains two additional specimens from the same locality (Coll. No.
190). Cat. No. 249758, U.S.N.M., contains two specimens from the
same source (Coll. No. 1030).
There is considerable variation in the width of the umbilicus of
this species, the following two having an umbilicus fully twice as
wide as the specimens alluded to above. In addition to this increased
width of umbilicus, they also have a little larger number of
axial riblets. Cat. No. 249756, U.S.N.M., one specimen from Port
Alfred (Coll. No. 1028). Cat. No. 186823, U.S.N.M., another specimen
from the same place (Coll. No. 189). Cat. No. 250560a, U.S.N.M.,
contains a very young tip of another specimen from the same place
(Coll. No. 1433a).
HELIACUS LUTETTS Lamarck.
Cat. No. 102725, U.S.N.M., a specimen from the Cape of Good
Hope.
HELIACUS, species?
Cat. No. 250502, U.S.N.M., contains a young Heliacus from Port
Alfred which is smooth, excepting a band at the periphery and two