APPENDIX. 235 



the Pitt's Bank, must, after what has been shown of 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, with some low islets on its eastern edge, and 

 likewise some on the western side, between which there is a 

 depth of about twelve 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 unintelligible 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 de- 

 scribed in the chapter on fringing-reefs ; coloured red. — 

 Rodriguez. The coral-reefs here are exceedingly extensive ; 

 in one part they project even five miles from the shore. 

 As far as I can make out, there is no deep-water moat 

 within them ; and the sea outside does not deepen very 

 suddenly. The 0'itline, however, of the land appears to be 

 {Life of Sir J. Makintosh, vol. ii. p. 165) hilly and rugged. 

 I am unable to decide whether these reefs belong to the 

 barrier class, as seems probable from their great extension, 

 or to the fringing class ; uncoloured. — Bourbon. The 

 greater part of the shores of this island are without reefs ; 

 but Capt. Carmichael (Hooker's Bot. Misc.) states that a 

 portion, fifteen miles in length, on the S.E. side, is imper- 

 fectly fringed with coral-reefs : I have not thought this 

 sufficient to colour the island. 



Seychelles. — The rocky islands of primary formation, 

 composing this group, rise from a very extensive and 

 tolerably level bank, having a depth between 20 and 40 



