154 THE CORAL REEFS OF THE MALDIVES. 



The bottom at anchor off Gadu, in twenty-eight fathoms, was hard, 

 swept clean by currents. 



Sounding in thirty-nine fathoms in the centre of the northern part of 

 Suvadiva, we brought up a piece of Millepora evidently cut off from a living 

 cluster. This is a far greater depth, I believe, than that at which any reef 

 builder has as yet been dredged. In making a second sounding nearly in 

 the same position, we found the bottom to consist of Corallines, Coralline 

 fragments, and sand and ooze. 



The bottom off Gan (Addu), in twenty-two fathoms, was somewhat sticky 

 and consisted of coarse coral sand mixed with Corallines and broken shells ; 

 we brought up in the dredge a number of specimens of species of Balano- 

 phyllia. In all, the smooth base was perforated near one extremity by an 

 opening leading into a cavity occupied by a small Sipunculoid. 



