246 APPENDIX. 



ward, is only about 30 fathoms. The part above specified is 

 engraved on a large scale ; and as in the charts on rather a 

 smaller scale the same fringe of reef extends as far as lat. 

 33° 15', I have coloured the whole of this part of the coast 

 red. The islands of Juan de Nova (in lat, 17° S.) appear in 

 the charts on a large scale to be fringed, but I have not been 

 able to ascertain whether the reefs are of coral ; uncoloured. 

 The main part of the west coast appears to be low, with out- 

 lying sand banks, which Lieut. Boteler (vol. ii. p. 106) says, 

 * are faced on the edge of deep water by a line of sharp-pointed 

 coral-rocks.' Nevertheless I have not coloured this part, as I 

 cannot make out by the charts that the coast itself is fringed. 

 The headlands of Narrenda and Passandava Bays (14° 40') 

 and the islands in front of Radama harbour are presented in 

 the plans as regularly fringed, and have accordingly been 

 coloured red. With respect to the East coast of Madagascar, 

 Dr. Allan informs me, that the whole line of coast, from Tam- 

 atave in 18° 12' to C. Amber at the extreme northern point of 

 the island, is bordered by coral-reefs. The land is low, un- 

 even, and gradually rises from the coast. From Captain 

 Owen's charts, the existence of reefs, which evidently belong to 

 the fringing class, N. of British Sound and near Ngoncy, might 

 also have been inferred. Lieut. Boteler (vol. i. p. 155) speaks 

 of ' the reef surrounding the island of St. Mary's at a small 

 distance from the shore.' In a previous chapter I have de- 

 scribed, from the information of Dr. Allan, the manner in 

 which the reefs extend in N.E. lines from the headlands on 

 this coast, thus sometimes forming rather deep channels within 

 them : this seems caused by the currents, the reefs springing 

 up from the submarine prolongations of the sandy headlands. 

 The above specified portion of the coast is coloured red. The 

 remaining S.E. portions do not appear in any published chart 

 to possess reefs of any kind ; and the Rev. W. Ellis believes 

 that there are none. 



East Coast of Africa. — The northern parts appear, for 



