186 CORALS AND CORAL ISLANDS. 



Group, the shore platform is seldom as extensive as at the 

 Paumotus. ' It rarely exceeds fifty yards in width, and is cut 

 up by passages often reaching almost to the beach. In some 

 places the platform is broken into islets. Enderby's Island is 

 one of the number to which this description applies. The 

 beach is eleven or twelve feet high. For the first eight feet it 

 slopes very regularly at an angle of thirty to thirty-five degrees, 

 and consists of sand, coarse pebbles, or rounded stones of coral, 

 with some shells; and there is the usu&l beach conglomerate 

 near the water's edge. After this first slope, it is horizontal 

 for eighty to two hundred feet, and then there is a gradual 

 rise of three to four feet. Over this portion there are large 

 slabs of the beach conglomerate, along with masses from the 

 reef-rock, and some thick plates of ' a huge foliaceous Madre- 

 pora ; and these slabs, many of which are six feet square, lie 

 inclining quite regularly against one another, as if they had 

 been taken up and laid there by hand. They incline in the 

 same direction with the slope of the beach. The large Madre- 

 pora alluded to has the mode of growth of the Madrepora 

 palmata ; and probably the entire zoophyte extended over 

 an area twelve or fifteen feet in diameter. The fragments 

 are three to four inches thick, and thirty square feet in surface. 



As a key to the explanation of the peculiarities here ob- 

 served, it may be remarked that the tides in the Paumotus are 

 two to three feet, and about Enderby's Island five to six feet 

 in height. 



Maldive Archipelago.— -The Maldives have been often 

 appealed to in illustration of coral structures. They are par- 

 ticularly described by Mr. Darwin from information commu- 

 nicated to him by Captain Moresby, and from the charts of this 

 officer and Lieutenant Powell. A paper on the northern Mal- 

 dives, by Captain Moresby, is contained in the Journal of the 



