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as the hollow shells are, and which are uppermost, the flat shells seldom appear to have any 

 extraneous matter on them. Now, are the shells so difficult to see for the protection of the 

 creatures inside, and if so, from what kind of enemy I would ask is that enemy man only? 

 as if not, can we form any idea of the manner by which any other enemy might be able to 

 distinguish them? When the oyster does attach itself to a rock or other substance it does so 

 on the flat shell side. 



Then again, the cockle or cardium. Everyone knows that the two shells of a cockle are 

 alike, the only difference in them is the hinge and the beautiful toothlike arrangement adapted 

 to hold the two shells together ; but, to point out that no two things in Nature are exactly 

 alike, who ever found two cockle shells to fit each other exactly, excepting the identical pair 

 belonging to the creature? Then again, if we take the exotic heart-shaped cockle, it reminds 

 us of a flat fish, as it must only rest on its side, the two shells being almost flat, like a pecten, 

 but opening in the centre sideways. The animal must be a queer fellow to inhabit such a house. 



Operculums appear only to be for the animal's protection against enemies when at rest and 

 undisturbed by the rough sea, as when it is rough the animal has to hold on to the rocks by its 

 cleaver-like process to prevent its being washed away. Each kind has its enemy. The common 

 limpet's cleaver is very illustrative, and shews the creatures great power in adhering to the rock 

 when it desires to do so, and its covering renders an operculum unnecessary. When the tide is 

 out, we find the smaller buccinum or chuck attached to the rock by its cleaver, but when it is 

 disturbed (except by the waves, when it holds on harder), it falls, and the animal retires into 

 its shell, and closes itself in by the operculum. 



