Bulletin - United States National Museum - Smithsonian Institution

64 BULLETIN 91, UNITED STATES NATIONAL MUSEUM.
Genus ACRILLA H. Adams.
ACRILLA THALIA, new species.
Plate 17, figs. 5, 8.
Shell elongate-conic, light brown, with a narrow white band on the
middle of each whorl. Nuclear whorls decollated. Postnuclear
whorls decidedly rounded, separated by a strongly constricted
suture, marked by well developed, very regular, almost vertical
axial ribs, of which 18 occur upon the first of the remaining turns;
20 upon the second; 22 upon the thud and fourth; 26 upon the fifth;
28 upon the sixth, and 34 upon the seventh and the penultimate
turn. These ribs are about one third as wide as the spaces that
separate them. Intercostal spaces marked by irregularly dis-
tributed, feebly incised, spiral striations. Periphery of the last
whorl well rounded; marked by a poorly developed spiral cord.
Base moderately rounded, marked by the continuations of the axial
ribs, and feebly incised, spiral striations. Aperture oval; outer lip
thin, showing the external markings within; inner lip decidedly
curved and reflected; parietal wall glazed with a thin callus.
The type and another specimen, Cat. No. 186840, come from
Port Alfred (Coll. No. 207). The type has nine whorls remaining
and measures : Length, 33 mm. ; diameter, 8 mm. The other specimen
which has lost the nuclear whorls, having the nine succeeding turns,
measures: Length, 17 mm.; diameter, 4.3 mm.
Genus GRAPHIS Jeffreys.
GRAPHIS AFRICANA, new species.
Plate 36, fig. 10.
Shell very minute, slender, elongate-conic, translucent. Nuclear
whorls a little more than two, somewhat inflated, ' smooth. Postnuclear
whorls well rounded, appressed at the summit, marked by
almost vertical, somewhat sinuous axial riblets, of which 18 occur
upon the first, 22 upon the second and third, 24 upon the fourth and
fifth, and 26 upon the penultimate turn. These riblets are about
one-half as wide as the spaces that separate them. Intercostal
spaces crossed by slender spiral threads, of which about 15 occur
between the sutures on the later whorls. Periphery of the last
whorl well rounded. Base moderately prolonged, well rounded,
marked posteriorly by the feeble continuations of the axial ribs,
which vanish before crossing half of the base, and numerous, very
fine, incised, spiral striations. Aperture broadly oval; posterior angle
obtuse; outer lip thin, showing the external sculpture within; inner
lip thin and slightly reflected.
The type, Cat. No. 249703, U.S.N.M., comes from Port Alfred
(Coll. No. 975). It has six and a half postnuclear whorls and
measures: Length, 2.3 mm.; diameter, 0.5 mm. Cat. No. 249708,
U.S.N .M. (Coll. No. 980), contains one specimen from Port Alfred.