2G4 
APPENDIX. 
twenty miles long, less than a mile in width (but expanding 
at the northern end into a disk), slightly sinuous, and 
parallel to the main land at the distance of five miles from 
it, with very deep water inside, so that in one place sound- 
ings were not obtained with 205 fathoms. Some leagues 
further south, there is another very narrow reef, ten miles 
long, with other small portions of reef, north and south, 
almost connected with it ; and within this line of reefs (as 
well as outside) the water is profoundly deep. There are 
also some small linear and sickle-formed reefs, lying a 
little way out at sea. All these reefs are covered, as I am 
informed by Captain Moresby, by living corals. Here, then, 
we have all the characters of reefs of the barrier class, and 
some of the outlying reefs partially resemble atolls. My 
only source of doubt arises from the narrowness and 
straightness of the spits of sand and rock in the Dhalac 
and Farsan groups ; one of these spits in the former group 
is nearly fifteen miles long, only two broad, and is bordered 
on each side with deep water ; so that, if worn down by 
the surf, and coated with living corals, it would form a reef 
nearly similar to those within the space under considera- 
tion. Nevertheless I cannot believe that the many small, 
isolated, and sickle-formed reefs, as well as others long, 
nearly straight, and very narrow, with the water unfathom- 
ably deep close round them, could have been formed by 
corals merely coating banks of sediment or the abraded 
surfaces of irregularly shaped islands. It seems more pro- 
bable that the foundations of these reefs have subsided, and 
that the corals, during their upward growth, have given to 
them their present forms. I have, therefore, with much 
hesitation coloured this part blue. 
The West Coast, from Lat. 22° to 24°. — This part of 
the coast (north of the space coloured blue on the map) is 
fronted by an irregularly shelving bank, from 10 to 30 
fathoms deep ; numerous little reefs, some of which have 
