Oysters and Scallops 8i 



captured and destroyed ; but a more insidious foe is 

 not evident until its mischief is done. This is a small 

 orange sponge {Cliona) that bores a network of 

 tunnels ramifying com.pletely throughout the shell, 

 rendering it rotten, and compelling the Oyster con- 

 stantly to deposit new layers of shelly matter within 

 to keep the intruder out. Whelks and other mollusks 

 with drilling power bore through the shells and eat 

 out the Oyster ; whilst the octopus with his parrot- 

 like beak, and the skate with its powerful teeth, also 

 add to the destruction. The Oyster occurs naturally 

 on all our coasts ranging in depth from low Avater to 

 about 45 fathoms. 



The Scallops (Fecten) are not only the near 

 allies of the Oyster, but some of them sliare the 

 same beds with their more valuable relatives. 

 Though the Oyster is more highly esteemed on 

 account of its commercial and gastronomic import- 

 ance, the Scallops must be pronounced at once more 

 beautiful and more interestinof. The shell is more 

 nearly symmetrical, though the valves are usually 

 unequal, and the strong even ribs with which the 

 surfaces are ornamented has made the shell familiar 

 in decoration of many kinds. This shell though 

 strong is thin, though hard is' light. The strength 

 is largely due to the hollow ribs, which make 

 possible the lightness necessary for submarine flight, 

 small Scallops and Quins being remarkable for 

 their power of rapidly flitting with a zigzag course 

 through the water by the opening and rapid closing 

 of their valves. A glance at the interior even of 

 an empty shell will show that the muscle for 

 closing the valves is very large, and must conse- 



