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160 American Seash ells
Yi inch or less in length, slightly fusiform with very slightly convex
sides to the spire. Suture almost impossible to see. Color glossy yellow-brown
with 2 rows of glassy, whitish, rounded beads. A third much weaker row
of beads, or an additional spiral thread, may appear in the last 2 or 3 whorls.
Axial threads connecting the beads are weak and form small pits. Fairly
common under stones along the low-tide zone.
Family JANTHINIDAE
Genus Janth'ma Roding 1798
Subgenus Janthina s. str.
Janthina janthina Linne Common Purple Sea-snail
Pelagic in warm waters; both coasts of the United States.
Plate 4)
I to 1/4 inches in diameter. Whorls slightly angular. Two-toned,
with purplish white above and deep purplish violet below. Outer Hp very
slightly sinuate. Common after certain easterly blows along the south-
eastern United States, especially from April to May. This is /. fragilis
Lamarck.
Subgenus Violetta Tredale 1929
Janthina globosa Swainson Globe Purple Sea-snail
Cast ashore along both coasts of the United States.
Plate 4k
/4 to % inch in diameter. Whorls globose, well-rounded. Color violet
throughout. Outer lip very slightly sinuate. Not very common.
Subgenus Jodina Morch i860
Janthina exigua Lamarck Dwarf Purple Sea-snail
Cast ashore in most warm seas.
Plate 4I
% inch in length. Whorls slightly flattened from above. Outer lip with
a prominent notch. Light-violet, banded at the suture. Fairly common.
/. bifida Nuttall is probably this species.
NOTE
Superfamily PYRAMIDELLACEA
The families Pyrafiiidellidae, Aclididae, Eulimidae, Styliferidae and
Efitoconchidae, most of which are small parasitic gastropods, have in the
past been placed here among the prosobranchs, but are now considered to