214 Common Periwinkle^ Size, Habits. 



industry. Moreover, it is a useful animal to the oyster-culturist. 

 When the latter's grounds are subject to weed, advantage is 

 taken of its grazing habits, and numbers of them are regularly 

 laid down to clean the pits, which their rasping tongues 

 effectually do. 



The average dimensions of the trade " winkle " is about 

 1 by f inch, first class being 1J by nearly f inch. Among con- 

 signments sent to Billingsgate from the north of Scotland still 

 longer ones occur. Of those bred and reared in our District, 

 they seldom run more than an inch long ; though occasionally 

 there are larger fellows found near or on those beds where 

 winkles are brought from market to be deposited only 

 temporarily. 



The common periwinkle, in contradistinction to No. 2, 

 deposits eggs (therefore oviparous). Their patches of eggs, 

 loosely stuck together by gelatinous substance, as well as 

 diminutive, crawling, shelled fry, here and there, are in profusion 

 on weeds, zostera, stones, &c. The adults are found in breeding 

 condition all summer, occasionally even up to November, weather 

 exercising an influence as to early or late procreation. The 

 eggs hatch quickly. We have not followed the rate of their 

 early stages of growth ; but those of half-an-inch are supposed 

 to be a year and some months old. At two up to three years 

 they attain a marketable size. 



Usually " winkles " are scattered about singly on stones, 

 gravel, posts, shells or zostera, and among the oysters and 

 mussels, or on weeds in the shallow muddy pools in the 

 brackish water, even on rocks high and dry. At other times 

 during the season they congregate, and even are said occasionally 

 to take to travelling or shifting of feeding ground en masse. 

 On the Essex shore, Leigh and Southend neighbourhood, some 

 are worn and roughened, chiefly at the spire end. This erosion 

 may be due either to the sand wash of the tides or other cause.* 



* Shrubsole in Conch. Jour. II., ascribes this erosion to an excess of lime in the 

 water calcic, carb. giving off carbonic acid. See also Jeffr. Brit. Conch. I. Introd. 

 Erosion. 



