13RTOZOA AND ANTHOZOA. 217 



Stutchberry, Ehrenberg, and Beechey, and now confirmed by 

 Darwin's observations, enable us to reason more correctly 

 on the importance and extent of the labours of Polypifera 

 in relation to the history of the earth itself, and of the higher 

 classes of the animal series : for when we compare the stu- 

 pendous results obtained by the operations of a community 

 of polyps with the boasted monuments of man, the latter 

 sink into insignificance. The great wall of China, or the 

 pyramids of Egypt's plains, are as nothing when contrasted 

 with the barrier-reefs that stretch along the shore of New 

 Caledonia to the length of four hundred miles, or those 

 which run along the north-east coast of Australia for up- 

 wards of a thousand miles. 



How marvellous is the reflection, that these masses of 

 calcareous rock have been secreted, through successive ages, 

 by generations of tiny architects, amidst the waters of the 

 ocean, and in defiance of the violence of its ever restless waves ! 



The study of such phenomena prepares the mind of the 

 geologist for the investigation of operations of a similar cha- 

 racter which have taken place in the seas of former periods 

 of the earth's history. Many palaeozoic and oolitic rocks may 

 be said to be ancient coral reefs, and appear to have been 

 formed under conditions analogous to those which are now 

 in progress in the waters of the Pacific. 



We divide this class into two orders 



BRYOZOA ANTtfOZOA. 



The BRYOZOA includes the most highly- organised 

 Polyps. The tentacula are ciliated; the digestive organs 

 have an intestine and rudimentary gland ; the body has no 

 septal divisions, and they possess a type of structure which 

 connects them with some of the Molluscan class. This order 

 includes the families ESCHABAD.&, TTTBULIPOBID^;, MTEIO- 



PORLD-E, ASTEKODISCIDJE, 



The ANTHOZOA have unciliated tentacula, no intestinal 

 appendage to the stomach, and have the body of the polyp 

 divided by septa, which produce stellate laminated cells on 

 the polypary. 



The cells seen on the surface of Astrea, Madrepora, 



