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 Operculum littorinid, and is withdrawn well 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 



Plate 19b 



Labrador to New Jersey. Western Europe. 



% 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 



Plate 19c 



New York to north Florida to Texas. 



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 



Plate 196 



South half of Florida to Texas, the West Indies and Bermuda. 



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, 



