Bulletin - United States National Museum - Smithsonian Institution

SOUTH AFRICAN MARINE MOLLUSKS. 155
GIBBULA ARTICULATA Gould.
Plate 25, figs. 4, 5, 6.
Margarita articulata Gould, Proc. Bost. Soc. Nat. Hist., vol. 8, p. 15, 1861.
Shell horn colored with spots of brown, which equally divide the
space with ground color on the spiral keels. There is a line of commashaped
spots which extend from the summit into the flat space ante-
rior to it. Nuclear whorls two and one-half, small, well rounded,
smooth, white. Postnuclear whorls three and one-third, the first
two marked by three strong lamellar spiral keels, the last by four
between the summit and the periphery. The keels are equally spaced,
the fourth being at the periphery, while the first is a little further
from the summit than it is from its neighbor anteriorly. In addition
to the spiral sculpture, the whorls are marked by very slender, closely
spaced, axial threads which are best developed in the spaces between
the spiral cords. Periphery and base well rounded, the latter broadly
umbilicated and marked by 10 depressed spiral cords which are trun-
cated posteriorly and slope gently anteriorly, the whole having the
appearance of a series of imbricating bands. In addition to these,
there are three cords in the umbilicus wider and stronger than those
on the base. These cords are crossed by closely spaced riblets which
give them a peculiarly notched appearance. Aperture subcircular;
outer lip rendered sinuous by the spiral keels; columella slender,
strongly curved; parietal wall covered with a thin callus.
Gould's type, Cat. No. 121, U.S.N.M., was collected by William
Stimpson on the North Pacific Exploring Expedition at Simons Bay,
Cape of Good Hope. It has 3 J postnuclear whorls and measures:
Altitude, 6 mm.; greater diameter, 7 mm.; lesser diameter, 6 mm.
Two additional lots are in the United States National Museum. Cat.
No. 90108, U.S.N.M., one specimenfrom the Capeof Good Hope. Cat.
No. 187106, U.S.N. M., one specimen from Port Alfred (Coll. No. 651).
GIBBULA FUCATA Gould.
Plate 27, figs. 4, 5, 6.
Gibbulafucata Gould, Proc. Bost. Soc. Nat. Hist., vol. 8, p. 20, 1861.
Shell elevated, helicoid, apex red, the rest variously spotted,
streaked and blotched with Indian red, pale yellow, light green and
brown. Nuclear whorls two and one-half, well rounded, smooth.
Postnuclear whorls marked by four, very strong, rounded, equal, and
equally spaced, spiral cords, of which the first is at the summit and the
fourth at the periphery. On the last turn the cord at the summit becomes
obsolete. In addition to the spiral sculpture the whorls are
marked by very retractively slanting, closely spaced lines of growth.
Periphery of the last whorl rendered decidedly angulated by the
spiral cord. Base short, well rounded, marked on the posterior fourth