304 THE SEAS 



mussel bed, such as the one shown in Plate 109, consists, not 

 of scattered animals, but of a solid mass of mussels of all 

 sizes often six inches deep. The shell is not itself attached, 

 but the animal discharges a series of fine, viscid threads 

 known as " byssus," which are directed by way of a groove 

 on the thin, extensible " foot " on to a convenient surface 

 against which they adhere. They quickly harden in sea 

 water and form an extremely strong attachment so that 

 it takes the most violent storm to break up mussel beds 

 although these are often found on mud flats or stretches of 

 sand. So rich are these beds that it is seldom necessary 

 to cultivate mussels, although it has been found by ex- 

 periments on the Lancashire coast that small, stunted 

 mussels from overcrowded areas speedily grow to large 

 marketable size when transplanted to new areas. Many 

 mussel beds are exposed at low water and the mussels 

 collected by hand, but others are always under water 

 so that they have to be fished from boats by means of 

 dredges. 



Mussels are, however, cultivated on the west coast 

 of France in the shallow, muddy bay called Anse de 

 L'Aiguillon. The system of cultivation employed dates 

 back some seven hundred years to the chance which 

 wrecked an Irishman called Walton, travelling on a small 

 vessel containing sheep, in this region in 1235. He and 

 some of the sheep — from which it is said certain valuable 

 modern flocks are the descendants — were the only 

 survivors and, in order to obtain a living, he tried to snare 

 sea birds by means of rough grass nets fastened to stakes 

 on the muddy shores. It is doubtful whether he caught 

 the birds, but quite incidentally he discovered a more 

 reliable food supply, for young mussels speedily covered 

 his nets and, because they were raised above the mud in 

 which they would otherwise have been smothered, they 



