pes; it is amusing
to know that it has only been about one hundred and fifty years since it
was discovered not to be a plant but an animal! Even Ovid states the
popular belief of the classic period when he speaks of the coral as a
seaweed "which existed in a soft state as long as it remained in the
sea, but had the curious property of becoming hard on exposure to the
air."

These strange coral-producing animals of the deep demand two especially
important conditions only under which they will thrive: namely, a
certain depth of water and a certain temperature. Thus it is seen that
the warmth of the sea determines the distribution of the corals; the
geography of these animals is defined by degrees of temperature. Only in
equatorial seas may reef-building corals be found; and if we select the
"Equator as a natural centre of the globe, and measure off a band of
1800 miles in breadth on each side of that line," we will find that it
will include the chief coral regions of the earth.

The work of the corals is most interesting. Small as are these tiny
workmen, each and every one does his bit and, speck by speck, adds his
minute contribution to the growing mass of coral until entire islands
are surrounded by extensive reefs. Tahiti, for example, is surrounded by
a barrier reef which is really an immense wall. The large barrier reef
on the northeast coast of Australia extends in a continuous line for
1,000 miles, and varies from 10 to 90 miles in breadth. Some reefs are
mere fringes which simply skirt the coast lands, and seem to be mere
extensions of the beach. Still another variety of reef is known as the
"atoll" or "lagoon" reef. This latter form is seen in circular rings of
coral of various breadths which enclose a body of still water--the
lagoon. There are many of these coral islands in the Indian and Pacific
Oceans. Keeling or Cocos Atoll, of the Indian Ocean, is 9-1/2 miles in
its greatest width; Bow Island is 30 miles in length, and 6 miles wide;
while in the Maldive Archipelago one island measures 88 geographical
miles in length, and in some places is 20 miles wide. When one beholds a
large coral ring, covered with rich soil and tropical vegetation, and
"protecting a quiet lake-haven from the restless ocean without, it is
little to be wondered at that the earlier voyagers recorded their
surprise that the apparently insignificant architects of such an
erection are able to withstand the force of the waves and to preserve