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APPENDIX. 
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 ‘ thereef 
surrounding the island of St. Mary's at a small distance 
from the shore.’ In a previous chapter I have described; 
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 spring- 
ing up from the submarine prolongations of the sandy head- 
lands. The above specified portion of the coast is coloured 
red. 1 The remaining S.E. portions do not appear in any 
published chart to possess reefs of any kind ; and the Bev. 
W. Ellis believes that there are none. 
East Coast of Africa. — The northern parts appear, for 
a considerable space, to be without reefs. My information, 
I may observe, is derived from the survey by Captain Owen, 
togetlier with his Narrative ; and that by Lieut. Boteler. 
At Mukdeesha (2° 1' N.) there is a coral-reef extending 
four or five miles along the shore (Owen’s Nar. vol. i. 
p. 357), which in the chart lies at a distance of a quarter of 
a mile from the shore, and has within it from 6 to 10 feet 
of water : this then is a fringing-reef and is coloured red. 
From Juba, a little S. of the equator, to Lamoo (in 2° 20' 
S.) ‘ the coast and islands are formed of madrepore ’ 
(Owen’s Narrative, vol. i. p. 3G3). The chart of this part 
(entitled Dundas Islands) presents an extraordinary ap- 
pearance ; the coast of the mainland is quite straight, and 
is fronted at the average distance of two miles, by exceed- 
ingly narrow, straight islets, fringed with reefs. Within 
this chain of islets, there are extensive tidal flats and 
muddy bays, into which many rivers enter : the depth of 
these spaces varies from one to four fathoms — the latter 
1 [The northern end of Madagascar, of volcanic origin, has upraised 
coral, and is fringed with living coral.— Capt. Wharton.] 
