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A. JR. Honcood — Molluscan Shell-laijers. 



Iu order that there may be, further, no need to confuse the nature 

 or composition of the shell-layers of either fossil or recent shells, we 

 »ive below some of the differences or tests that serve to distinguish the 

 two forms of carbonate of lime in shells. 



An aragonite shell will scratch a calcite shell. 



