ORDER III. CORALLIFERI.—THE CORALS. 
eo 
Gr 
~1 
ORDER III. CORALLIFERI. 
This order includes many species which were once regarded as marine 
plants, but are now known to belong to the animal kingdom. The individ- 
uals are multitudinous, and so united as to form compound animals, gener- 
ally fixed like plants, by a branched stem, or by simple expansions of a 
solid substance at the base, or in the middle of the group. All are con-: 
nected in a common body, and have a general nutrition, so that whatever 
one eats contributes to the nourishment of the common body, thus forming 
a most extraordinary republic. 
The Greek name Polypidom — house of the Polypi—is usually given 
to the common part of these compound animals. “These polypidoms are 
formed in layers by deposition, somewhat similar to the ivory of teeth; and 
they are of various degrees of hardness, the hind parts being composed of 
salts of lime, but always united by means of animal matter.” 
These apparently insignificant creatures, often so minute as to escape the 
eye of man, perform labors in the ocean depths in comparison with which 
the proudest and grandest monuments of human skill must be considered as 
nothing. They’are the invisible architects which construct new islands and 
enlarge the boundaries of continents. 
The prodigious surface over which their combined and ceaseless toil ex- 
tends, ought to be taken into consideration in order to understand the 
important part they play in nature. They haye built a barrier of reefs four 
hundred miles long round New Caledonia, and another which extends along 
the north-east coast of Australia one thousand miles in length. “This 
represents,” says an illustrious zodlogist, “a mass in comparison with which 
the walls of Babylon and the Pyramids of Egypt are child’s toys. And 
these edifices of the Polypi have been reared in the midst of the ocean wave, 
and in defiance of tempests which so rapidly annihilate the strongest works 
constructed by man.” Notwithstanding their extreme minuteness, the Polypi 
have nevertheless, by their calcareous buildings, reacted powerfully on the 
crust of the terrestrial globe. They have modified it in two ways — by rais- 
ing the bed of the sea, and by forming large calcareous mountains with their 
débris ; in fact, when we examine the layers of which these are composed, 
we perceive that they are formed entirely of polypoids and bivalves which 
swarmed in the ancient oceans of the globe. 
Ground to dust by the furious waves, these creatures have only here and 
there left a few traces to attest their presence, and serve as a light to the 
modern investigators of science. 
Such is the opinion of Lyell, and most modern geologists. In support 
NO. XX. 95 
