CHAPTER XXXVI : THE PERIWINKLES AND 



CHINK SHELLS 



Family Littorinid.^ 



Shell spiral, turbinate or globular, not pearly; aperture 

 oval or circular, entire; lip simple; columella thickened, flattened; 

 operculum horny, of few coils ; snout wide, short ; eyes on swellings 

 at outer bases of the long tentacles; foot broad and square in 

 front and behind, divided lengthwise; radula long and narrow. 

 Reproduction by eggs hatched within or outside the body. 



Genus LITTORINA, Fer. 



Characters of the family. A large genus of 150 species, 

 living on rocks between tide marks. Some live in brackish, 

 some in fresh water. Some species are amphibious and can 

 survive long periods of drought. Som.e live on aerial roots of 

 mangrove trees, where they overhang the water and get the dash 

 of its spray. The distribution of the genus is world-wide. It 

 is rapidly spreading on American coasts. 



Periwinkles furnish an important article of food to European 

 markets, where they are bought by the poorer and middle 

 classes. They are also an important bait for fish. 



The Shore Periwinkle (L. littorea, Linn.) is a mollusk 

 fitted by nature to survive in the struggle for existence. Abundant 

 on all the shores of Northern Europe, it has colonised New Eng- 

 land and is rapidly extending its range southward. Its solid 

 shell and horny operculum make an impregnable fortress against 

 foes without. 



The name periwinkle, is an old one. It is supposed to be 

 modified from "petty winkle," the small one, to distinguish it 

 in the London markets from the large winkle, or whelk, Buccinum 

 undatum. Both are staple foods in England. Thousands of tons 

 of this dingy little mollusk are collected each year for the city 

 trade by women and children on the rocky coasts of the British 



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