16 FORM OF A MASS OF REEF. 



feature among them is a line of great detached 

 blocks lying a little back from the outer edge of the 

 reef, frequently not altogether covered even at high 

 tide, and always quite exposed at low water. I landed 

 on one reef from our anchorage of the evening of the 

 5th. We carried blue water from the ship for about 

 half a mile, and then began to see the bottom in 

 about seven fathoms, from which it shoaled gra- 

 dually, but rapidly, till the boat touched the top of 

 the coral branches. Scraping on, however, over 

 these, and winding between the more solid masses of 

 maeandrina and astrsea, we reached some of the 

 large dry blocks on the seaward edge of the reef. 

 I found some of them to be hu^e masses of ma?an- 

 drina, six or eigbt feet in diameter, much water- 

 worn, and lying upside down, having been torn by 

 some heavy sea from their place of growth on the 

 weather edge of the reef, and washed two or three 

 hundred yards back from it. Others were a species 

 of massive porites, while others again consisted of 

 various corals, all matted and compacted together. 

 After wading about for a short time knee-deep, and 

 collecting a few shells, holothuriae, Crustacea, and 

 echinodermata, the flood-tide began to make, run- 

 ning in in a very rapid stream over the edge of the 

 reef, and obliging us to hasten back to the boat. I 

 got one or two very beautiful comatula3, one espe- 

 cially of a rich dark purple or wine colour, almost 

 black, but did not succeed in my first attempt to 

 preserve it. I kept it in salt water during the night, 



