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132 American Seashells
utina. Early whorls purplish brown, last whorl translucent, light chestnut-
brown. Shell covered by a thin varnish of periostracum of the same color.
At the edge of the thin, smooth outer lip, the periostracum is neatly curled
back to form a minute ridge. Umbilicus slit-like, with the periostracum
puckered along its length. Operculum littorinid, and is withdrawn well
within the glossy-brown aperture. Not uncommon in shallow water.
Genus Littorina Ferussac 1821
Littorina littorea Linne Common Periwinkle
Labrador to New Jersey. Western Europe.
Plate 19b
% to I inch in length, thick, smoothish. Gray to brownish gray in color.
Inside of aperture chocolate-brown. Columella and inner edge of aperture
whitish. In young or perfect specimens there are fine, irregularly spaced,
spiral threads with microscopic, wavy wrinkles in between. Introduced from
Europe some time before 1840. A favorite food in Europe. Very common
along the rocky shores of New England.
Littorina irrorata Say Marsh Periwinkle
New York to north Florida to Texas.
Plate 19c
About I inch in length, thick-shelled, with numerous, regularly formed
spiral grooves. Outer lip strong, sharp, slightly flaring, and with tiny grooves
on the inside. Color usually grayish white with tiny, short streaks of reddish
brown on the spiral ridges. Aperture yellowish white. Callus of inner lip
and the columella pale reddish brown. Commonly found in large numbers
among the sedges of brackish water marshes. Not recorded alive south of
Indian River (east Florida) or Charlotte Harbor (west Florida).
Littorina ziczac Gmelin Zebra Periwinkle
South half of Florida to Texas, the West Indies and Bermuda.
Plate 196
Females about i inch, males about V2 inch in length. Shell fairly thick
and strong. Base angulate; aperture purplish brown. Columella various
shades of dark-brown. Outer shell white to bluish white with many narrow,
zigzag, oblique lines of chestnut-brown or purplish brown. Early whorls
uniformly pale reddish brown. Female shells: higher than wide, smoothish.
Male shells: as high as wide, with strong spiral grooves. Operculum dark-
brown. Abundant in crevices between tides in rocky areas. Introduced to
the Pacific side of the Panama Canal. Do not confuse with the larger and
thinner-shelled L. angulifera whose operculum is light-brown, not dark-
brown, in color,