SOME ECONOMIC ASPECTS OF SHORE LIFE 287 



more suitable areas where they may either remain submerged 

 in brackish water (the " bed " system) or attached to arti- 

 ficial supports of brushwood, etc. (the " fascine " or 

 " bouchot " system of the French and other coasts), where 

 food is especially abundant, they make such rapid increase 

 in flesh as to render transplantation a profitable commercial 

 transaction. 



Periwinkles {Littorina littorea) often occur in great 

 numbers on boulder-strewn shores, estuarine areas that are 

 gravelly, etc., and also among mussels, where they can obtain 

 firm foothold and some shelter from storms. The winkle 

 is a vegetarian and browses upon algae and their young growth. 

 Piel, near Barrow-in-Furness, is one of the centres of the 

 industry on the west coast of England, and some figures 

 and details have been published by Scott (191 7). The 

 molluscs are collected by hand, the bulk between October 

 and May ; the average annual quantity sent to the inland 

 towns of Lancashire, and to London, from 1906 to 1914, 

 was about 48 tons, valued at ;^240 per annum. A bag of 

 winkles contains 136 pints and weighs i| cwts. ; there are 

 about 125 winkles in a pint, so that the average bag contains 

 some 17,000. In the twelve years 1906-17, over 500 tons 

 have been despatched from Piel Station alone, the value to 

 the fishermen being at least ,(^2680. In certain cases such 

 shell-fish as Solen (the Razor Shell), My a arenaria (the 

 clam), Scrohicularia piperita and Venus gallina (both known 

 as " Hens "), Patella vulgata (the Hmpet), Buccinum iindatum 

 (whelk), Haliotis tuherculata (the " ormer " of the Channel 

 Islands), and others, may be made use of as food, but seldom 

 in any commercial sense. 



We may allude here to the extraction of dye from 

 molluscs. The forms used by the ancients were species of 

 Murex and Purpura. Other forms yielding coloured 

 secretions having the properties of dyes are the Sea-hare 

 (Aplysia) and lanthina. This industry, begun by the 

 Minoans of Crete, has now lost all commercial importance. 



Shore Crustacea. — On sandy and muddy coasts the 

 shrimping industry is of some importance. In some places, 



