246 
APPENDIX. 
belt of coral-rock, ‘ with a basin of deeper water in tlie 
centre,’ and deep sea close outside. — Bombay Slioal appears 
(Horsburgh, vol. ii. p. 432) ‘ to be a basin of smooth water 
surrounded by breakers.’ I have coloured these three 
shoals blue. — The Paraquas Shoals are of a circular form, 
with deep gaps running through them; not coloured. A 
bank, gradually shoaling to the depth of 30 fathoms, ex- 
tends to a distance of about 20 miles from the northern 
part of Borneo, and to 30 miles from the southern part of 
Palawan ; near the land this bank appears tolerably free 
from danger, but a little further out is thickly studded 
with coral-reefs, which do not generally rise to the surface ; 
some of them are very steep, whilst others have a fringe of 
slioal-water round them. I should have thought that these 
shoals had level surfaces, had it not been for a statement 
made by Horsburgh, ‘ that most of the shoals hereabouts 
are formed of a belt of coral : ’ I have not coloured them. — 
The coasts of China, Tonquin, and Cochin-China, forming 
the western boundary of the China Sea, appear to be with- 
out reefs : with regard to the two last-mentioned coasts, I 
judge from an examination of the charts on a large scale in 
the atlas of the Voyage of the Favourite. 
Indian Ocean. — South Keeling atoll has been specially 
described in my first chapter. Nine miles north of it lies 
North Keeling, a wry small atoll, surveyed by the Beagle, 
the lagoon of which is dry at low water. —Christmas Island, 1 
lying to the east, is a high island, without, as I have been 
1 [This island is described in letters to Nature by Captains Wharton 
and Maclear (vol. xxxvi. pp. 12, 413, and vol. xxxvii. p. 203 ; cf. also 
p. 222). It is 190 miles from Java, the intervening ocean attaining 
a depth of 2,430 fathoms. It consists of coral limestone, no other 
rock being visible, which rises from the sea to a height of about 
1,200 feet. At the base is commonly a cliff about 30 feet high, and 
there are two upper tiers of cliffs : one is described as being from 200 to 
300 feet high. A depth of 100 fathoms is found at one or two cables’ 
length from the water’s edge at the base of the lowest line of cliffs.] 
