134 American Seashells 



Littorina scutulata Gould Checkered Periwinkle 



Plate 20C 



Alaska to Lower California. 



% inch in length, moderately slender, semigloss finish and smooth. Color 

 light to dark reddish brown with small, irregular spots of bluish white. Colu- 

 mella white; interior of aperture whitish brown. A common littoral species. 

 Compare with L. planaxis. 



Littorina planaxis Philippi Eroded Periwinkle 



Plate 2oa 



Puget Sound to Lower California. 



^ to % inch in length, usually badly eroded; grayish brown with bluish 

 white spots and flecks. Characterized by the eroded, flattened area on the 

 body whorl just beside the columella. Interior of aperture chocolate-brown 

 with a white spiral band at the bottom. A common littoral, rock-loving spe- 

 cies. Do not confuse with the smoother, higher-spired L. scutulata. 



Littorina sitkana Philippi Sitka Periwinkle 



Plate 2ob 



Bering Sea to Puget Sound, Washington. 



% inch in length, solid, sharp lip, characterized by about a dozen strong 

 spiral threads on the body whorl. Columella whitish. Shell dark grayish to 

 rusty-brown; some with 2 or 3 wide spiral bands of whitish. A common 

 littoral species of the north. 



Genus N odilittorina Martens 1897 

 Nodilittorina tuberculata Menke Common Prickly-winkle 



Plate 191 



South Florida, the West Indies and Bermuda. 



^ to % inch in length. Shell rounded at the base. Several spiral rows 

 of small, fairly sharp nodules on the whorls. Columella flattened, forming a 

 slightly dished-out shelf. Color brownish gray. Operculum paucispiral. A 

 common rock-dwelling species found near the high-tide line. Do not con- 

 fuse with the extremely similar Echifiinus nodulosus Pfr. which has a multi- 

 spiral operculum, and whose columella is not shelved. Erroneously listed in 

 Johnsonia and other books as Tectarius tuberculatus Wood. 



Genus Tectarius Valenciennes 1833 

 Subgenus Cenchritis Martens 1900 



Tectarius muricatus Linne Beaded Periwinkle 



Plate iQg 



Lower Florida Keys, the West Indies and Bermuda. 



