3o6 THE SEAS 



the soft parts within the shell, which in the oyster are far 

 from beautiful are here highly attractive with their areas 

 of red, white and orange, marking the position of the repro- 

 ductive organs, the muscle and the gills respectively. 

 They are highly prized as food, two species being marketed 

 in the British Isles, and many others in different parts of 

 the world. Of the two former, one, the common scallop 

 {Pecien maximus), is of considerable size, four inches or 

 more in diameter and is considered a luxury, while the other 

 {Pecten opercularis) is about a quarter that size and is 

 often captured in large numbers off the south coast where 

 it is known locally as the " queen " and finds a ready sale, 

 being eaten raw like the oyster or else boiled. 



The edible cockle [Cardium edule) is probably familiar 

 to everyone. A good average specimen (Plate 109) is about 

 one inch long and has a rounded white shell covered with 

 small protuberances which enable it to grip the sand in which 

 it lives. It is an extremely common shellfish usually 

 living between tide-marks and is frequently found where 

 there is a stretch of sand sheltered from currents and from 

 the full force of the sea. Although it normally lies buried 

 in the sand so that one end of the shell is just flush with the 

 surface yet it can move about, either in the sand or on the 

 surface, by the help of a muscular " foot," a wedge-shaped 

 organ which is thrust out from between the two halves of 

 the shell. Like all bivalve molluscs, cockles live on micro- 

 organisms in the sea water and not on anything which 

 they may obtain from the sand ; and as a result, if there is 

 sufficient of the right kind of food in the water, the sand 

 may be literally packed with cockles lying " cheek by 

 jowl." It has been estimated that a single bed of som^e 

 320 acres in South Wales contains a population of about 

 462,000,000 cockles ! The young cockles spend a short 

 period swimming freely in the sea before they settle down 



