APPENDIX. 233 



reefs of coral have a- lagoon-like structure, they should 

 have been coloured blue, and they would have formed an 

 imperfect barrier in front of Palawan and the northern 

 part of Borneo. But, as the water is not very deep, these 

 reefs may have grown up from inequalities on the bank : 

 I have not coloured them. — The coast of China, Tonquin, 

 and Cochi?i- China, forming the western boundary of the China 

 Sea, appear to be without reefs : with regard to the two last- 

 mentioned coasts, I speak after examining the charts on a 

 large scale in the atlas of the voyage of the Favourite. 



Indian Ocean. — South Keeling atoll has been specially 

 described ; nine miles north of it lies North Keeling, a very 

 small atoll, surveyed by the Beagle, the lagoon of which is 

 dry at low water. — Christmas Island, lying to the east, is a 

 high island, without, as I have been informed by a person 

 who passed it, any reefs at all. — Ceylon : a space about 

 eighty miles in length of the S.-western and southern shores 

 of these islands has been described by Mr. Twynam (JVaut. 

 Mag., 1836, pp. 365 and 518); parts of this space appear 

 to be very regularly fringed by coral-reefs, which extend 

 from a quarter to half a mile from the shore. These reefs 

 are in places breached, and afford safe anchorage for the 

 small trading craft. Outside, the sea gradually deepens; 

 there is 40 fathoms about six miles off shore : this part I 

 have coloured red. In the published charts of Ceylon there 

 appear to be fringing-reefs in several parts of the south- 

 eastern shores, which I have also coloured red. — At Venloos 

 Bay the shore is likewise fringed. North of Trincomalee 

 there are also reefs of the same kind. The sea off the 

 northern part of Ceylon is exceedingly shallow ; and there- 

 fore I have not coloured the reefs which fringe portions of 

 its shores, and the adjoining islets, as well as the Indian 

 promontory of Madura. 



