218 
APPENDIX. 
had the same oi’igin with tlie other atoll-like hanks ; but as it 
does not deepen towards the centre, I have not coloured it. 
I might have referred to other authorities regarding these 
three archipelagoes ; but after the publication of the charts 
by Captain Moresby (to whose personal kindness in giving 
me much information I am exceedingly indebted), this 
would have been superfluous. 
The Sahia de Malha Bank consists of a series of narrow 
banks, with from 8 to 16 fathoms on them ; they are 
arranged in a semi-circular manner, round a space about 
40 fathoms in depth, sloping to the S.E. to unfathomable 
depths ; they are steep on both sides, but more especially 
on the ocean-side. Hence this bank closely resembles in 
structure, and I may add from Captain Moresby’s informa- 
tion in composition, Pitt’s Bank in the Chagos group ; and 
Pitt’s Bank must, from what we know about the great 
Chagos Bank, be considered as a sunken, half-destroyed 
atoll ; hence coloured blue.— Cargados Carajos Bank : its 
southern portion consists of a large, curved coral-shoal, 
w T ith some low islets on the eastern edge, and likewise 
some on the western side, between which there is a depth 
of about 12 fathoms : northward, a great bank extends. I 
cannot (probably owing to the want of perfect charts) refer 
this reef and bank to any class ; therefore not coloured. — 
lie de Sable is a little island, lying west of C. Carajos, only 
some toises in height (Voyage of the Favourite, vol. i. 
p. 130) ; it is surrounded by reefs ; but its structure is un- 
intelligible to me. There are some small banks north of 
it, of which I can find no clear account. — Mauritius : the 
reefs round this island have been described in the chapter 
on fringing-reefs ; coloured red. — Rodriguez : the coral- 
reefs here are very extensive ; in one part they project even 
five miles from the shore. As far as I can make out, there 
is no deep-water channel within them ; and the sea outside 
does not deepen very suddenly. The outline, however, of 
