90 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Rum Cay and Conception Island. 



Plate IX. Dig. 11. 



From the southwest poiut of Watliug Island we steamed to Rum 

 Cay, the structure of which is very similar to that of Watling. The 

 salt ponds are limited to two small areas, from which formerly a consid- 

 erable amount of salt was exported. 



On our passage from Watling Island to Rum Cay, and while sailing 

 round it and on our way to Clarence Harbor, we passed through many 

 streaks of gulf-weed. 



The bank of v.hich Rum Cay forms the summit extends northeast 

 about five miles to the 100 fathom line. The bank is narrow on the west 

 face. On the north side the 100 fathom line is not quite two miles from 

 shore, and varies from three miles to three and a half on the west and 

 south sides. On the eastern side the salt ponds are separated from the 

 sea by seolian hills varying from fifty to ninety feet in height, and on the 

 south by walls of recent coral sand. The northern and western ends of 

 the island are also capped by seolian hillocks. 



Rum Cay is about nine and a half miles in length by five in breadth 

 at the east end and two at the west. The southern side of the cay is 

 edged by a coral reef nearly a mile off shore, growing upon sunken 

 patches of seolian rocks. A wide entrance through the reef forms Port 

 Nelson inside the reef with four fathoms of water. There are patches 

 of corals all along the north shore about half a mile from it. The 

 corals are thriving, and consist, as far as we examined them, mainly of 

 huge masses of Astrseans, Orbicellas, Madrepora palmata, and Millepores. 



The low southeastern part of the island is formed of debris of the reefs 

 now growing on the southern edge of Port Nelson. A low bank of coral 

 sand is thrown up, forming strata slightly inclined and protecting the 

 coral sand flat extending inland to the base of the a^olian hills. The 

 north face is bold, steep, with low blufi's and no anchorage along it. 

 The east face is flanked by low seolian hills. The highest hills are 

 along the northern side near the northwest extremity of the island. 



Conception Island we did not visit. The adjacent cays rise to one 

 hundred and thirty feet above the circular bank, which carries from six 

 to fourteen fathoms of water. Reefs extend in a nearly unbroken line 

 round the southeastern and western edges of the bank. It is probable 

 that the 1,000 fathom line connects Conception Island Bank with the 

 southeastern side of Cat, and that Rum Cay also lies within that line. 



