122 ON CORAL AND CORAL REEFS 



longer or a shorter time, according as its position affords 

 more or less protection from the wear and tear of the 

 waves. 



The polypes which give rise to the white coral are 

 found, as has been said, in the seas of all parts of the 

 world ; but in the temperate and cold oceans they are 

 scattered and comparatively small in size, so that the 

 skeletons of those which die do not accumulate in any 

 considerable quantity. But it is otherwise in the greater 

 part of the ocean which lies in the warmer parts of the 

 world, comprised within a distance of about eighteen 

 hundred miles on each side of the equator. Within the 

 zone thus bounded, by far the greater part of the ocean 

 is inhabited by coral polypes, which not only form very 

 strong and large skeletons, but associate together into 

 great masses, like the thickets and the meadow turf, 

 or, better still, the accumulations of peat, to which 

 plants give rise on dry land. These masses of stony 

 matter, heaped up beneath the waters of the ocean, 

 become as dangerous to mariners as so much ordinary 

 rock, and to these, as to the common rock ridges, the 

 seaman gives the name of " reefs." 



Such coral reefs cover many thousand square miles in 

 the Pacific and in the Indian Oceans. There is one reef, 

 or rather great series of reefs, called the Barrier Reef, 

 which stretches, almost continuously, for more than 

 eleven hundred miles off the east coast of Australia. 

 Multitudes of the islands in the Pacific are either reefs 

 themselves, or are surrounded by reefs. The Red Sea 

 is in many parts almost a maze of such reefs, and they 

 abound no less in the West Indies, along the coast of 

 Florida, and even as far north as the Bahama Islands. 

 But it is a very remarkable circumstance that, within 

 the area of what we may call the "coral zone," there 



