The Periwinkles and Chink Shells 



Isles, and sold from corner stalls or push carts in the streets. 

 They are used as food in other European countries. The Portu- 

 guese of Provincetown and other points on Cape Cod gather 

 them in quantities. 



An immigrant from England, this species has come to our 

 coasts via Iceland and Newfoundland. Its invasion has rapidly 

 progressed southward past Cape Cod and Long Island to the 

 New Jersey beaches. On the rocky coasts of Maine it is found 

 in greatest abundance, covering the sides of huge boulders and 

 wharf piers exposed by the outgoing tide, clinging to seaweeds 

 and stems of marsh grass, or crawling in ditches, and tide pools. 



The shells are brownish yellow to olive or gray, sometimes 

 spirally banded with dark red and brown. Sometimes they are 

 black. There is great variability of colouring. They are thick, 

 with seven or eight whorls, ribbed spirally. There is no umbilicus ; 

 the lip is thin and black; the columella broad and white. The 

 aperture is round; the operculum horny. The spire is sharp, 

 but the shell has a squat shape, the base and height are each about 

 f inch. The males are smaller than the females. 



The periwinkle is a vegetarian, as are nearly all round- 

 mouthed snails. Coiled inside the mouth is the radula or rasping 

 tongue, about three times as long as the body (2 J inches); it 

 has six hundred rows of sharp, curved, tricuspid teeth, seven in 

 each crescentic row. Here is the weapon for scraping off the 

 algae which grows on rocks near shore. Knowing their feeding 

 habits, the owners of oyster beds scatter periwinkles on their 

 acreage to keep the hindering algae grazed close. 



The gait of the periwinkle is slow and uneven, one side 

 of the foot moving forward as the other holds fast : another good 

 instance of a "snail's pace." A median line divides the foot 

 lengthwise into two areas which act alternately in walking. A 

 gland in the foot secretes copious slime. The eggs are laid in 

 masses on seaweeds or rocks. 



The Common Periwinkle (L. irrorata, Say) is a heavy, 

 sharp-pointed conical shell, of a few finely ridged whorls. Num- 

 erous chestnut dots, in spiral lines, give a brownish colour to the 

 exterior; the smooth columella is also brown. The lipis thick but 

 bevelled suddenly to a thin edge and dotted with brown. This is 

 the periwinkle of the Gulf of Mexico, which has gradually pro- 

 gressed northward for years,overlappingthe range of theless robust 



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