THE subject upon which I wish to address you to-night is the structure and origin of Coral and Coral Reefs. Under the head of "coral" there are included two very different things; one of them is that substance which I imagine a great number of us have champed when we were very much younger than we are now, -the common red coral, which is used so much, as you know, for the edification and the delectation of children of tender years, and is also employed...