20 GREAT MASS OF REEFS. 



fathoms, more commonly the latter, with reefs in 

 every direction, as far as we could see, distinguish- 

 able even on the horizon by the light green of the 

 shoal water upon them. The bottom, as brought 

 up by the lead, was a coarse coral sand, composed 

 of rather worn but angular grains and fragments of 

 corals and shells, often the eighth of an inch in dia- 

 meter ; there were also many small chambered 

 shells or foraminifera, and many flat circular disks 

 were brought up sometimes as much as half an inch 

 in diameter, which are, I think, the marginopora of 

 De Blainville.* At 2 p.m., the sun having got to 

 the westward, cast a glare upon the water that hin- 

 dered us from seeing the channels between the reefs 

 ahead, and compelled us to anchor. 



Feb. 11, 12, 13. — Still sailing all morning to 

 the westward through the reefs, and anchoring in 

 the afternoon, the water perfectly smooth and the 

 weather delightful. About 11 a.m. of the 13th, 

 however, the reefs became fewer, and we began to 

 feel a slight swell, and the depth increased to 45 

 fathoms. At noon the character of the bottom had 

 changed from a coarse coral sand to a green sand 

 with black specks, which latter remained untouched 

 by muriatic acid, although the sand effervesced. 

 At 1 p.m. we saw an island which proved to be 

 " High Peak,'' and we found we were quite clear of 



* Professor Forbes, however, has, since my return, informed 

 me that he believes these are disks of acetabularia. 



