SUPPLEMENT. 1225 



Lobsters, prawns, and shrimps, as well as crabs, do a 

 vast amount of damage on an oyster laying. Their ravages 

 are committed during the w r arm months of summer and 

 autumn, when the shell is growing and the spat is floating 

 about in the sea. It is at this time they are most active, 

 and the amount of oysters destroyed before their shell has 

 time to harden is enormous. 



Besides crustaceans, many fish feed on the spat of 

 oysters. Mullet, whiting, mackerel, gobies, and all insec- 

 tivorous fish, will eat it greedily if it comes in their way. 



Shrimps and small fish lie under the shell of a breeding 

 oyster, waiting for the spat to be ejected. When this 

 has taken place, they dart out and devour it with great 

 avidity. 



Prawns will attack very young oysters with great suc- 

 cess ; rushing at the tender shell with their serrated beak, 

 backing well before they make each rush, they soon make 

 a hole sufncientlv large to enable them to obtain an 



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entrance and consume the young fish. 



WHELKS AND WHELK-TINGLES. 



Whelk-tingles are also called dog-whelks or boring 

 whelks (Purpura lapillus). They are one of the greatest, 

 if not the most destructive, of the oyster's enemies. 



This shell-fish has the power of protruding a rasp-like 

 borer out of the cylindrical apex of its shell. Under a 

 powerful magnifying glass the borer can be seen to be a 

 most formidable weapon, and the way they use it is as fol- 

 lows : Crawling over the oyster until seated with its borer 

 immediately above the heart, the most vital part of the 

 victim, the dog-whelk protrudes its head and body down- 

 wards to hold on and balance itself by, and then works 

 away with its borer until a hole, like that made by a drill, 



