8o Shell Life 



Oyster supply; and the Oysters have selected the 

 summer months as aftbrding the greatest chance of 

 success. A warm day and a quiet sea are the 

 favourable conditions required ; with a low temper- 

 ature and troubled waters there is every probability 

 of the spat being destroyed, or, what is almost as bad, 

 carried far out to sea. 



Left on their natural banks Oysters are full-grown 

 in about four years, but when dredged and laid down 

 again in the culture beds they take several years 

 longer. " Natives " are those supposed to have passed 

 the whole of their lives in the beds about the mouth 

 of the Thames and Medway, but many of them no 

 doubt are those that have been dredged in distant 

 parts of the coast, purchased by the Kent and Essex 

 merchants, and relaid for a year or so. Oyster- 

 dredging is regulated by local fishery bylaws, which 

 fix the minimum limit of size at which dredging is 

 legal ; 2| inches, for instance, being the minimum at 

 Falmouth, the Oyster then being about 2 J years old. 

 They are considered to live about ten years, but to 

 be at their best at five years, when the shell measures 

 as many inches across. The " Green Oysters," or 

 hidtres de Marennes, of Normandy have been 

 specially fattened on a green diatom {Navicula 

 ostrearia) in ponds rich in this particular form of 

 microscopic plant - life. In the course of several 

 years of this diet the Oyster in turn becomes green, 

 •and acquires a special flavour. 



Both on the natural sea-banks and the estuarine 

 beds to which they are transplanted, Oysters have a 

 number of enemies to contend with. Starfishes and 

 crabs are the best known of these, and they can be 



