SEA STABS OB STAEFISHES. 45 



Now we come to a group of marine creatures in 

 which the food-procuring structure is so remarkable, 

 that if it had not been seen in action no one could have 

 suspected it. Even dissection could have given no clue 

 to it. 



There are few marine animals which appear to be so 

 absolutely secured from foes as the bivalve molluscs, such 

 as the oyster, the scallop, the cockle, and the mussel. 

 Their lives appear, according to our ideas, to be peculiarly 

 dull and stupid, but there does seem to be a compensa- 

 tion in their immunity from foes. Among reptiles the 

 slow-moving tortoise presents a somewhat similar combi- 

 nation, but even the box-tortoise itself, which can contract 

 its legs and head within the shell, and then shut itself up 

 like a box, is not nearly so secure as either of these 

 molluscs. 



Supposing that a hungry man were supplied with 

 oysters, and forbidden the use of tools with which he 

 could either break the shells or force them open, he 

 would probably starve to death. If we were to be asked 

 to select some inhabitant of the sea which would be best 

 fitted for feeding on oysters, we should naturally search 

 for some large fish, furnished with teeth and jaws power- 

 ful enough to crush the firmly -closed shells, for to force 

 them asunder would be almost impossible. 



Any of my readers who has opened oysters, knows 

 practically that even with the aid of a knife made 

 expressly for the purpose, a novice in the art finds the 

 greatest difficulty in forcing the shells asunder. He cuts 



