252 
APPENDIX. 
distance of two miles from the shore ; in some parts, how- 
ever, the reef must be attached, since Lieut. Boteler (Narr. 
vol. i. p. 1G1) describes a passage through it, within which 
there is room only for a few boats. Its height, as I am 
informed by Dr. Allan, is about 3,500 feet ; it is very pre- 
cipitous, and is composed of granite, greenstone, and 
quartz ; coloured blue. — Mohilla : on the S. side of this 
island there is anchorage between a reef and the shore 
in from 30 to 45 fathoms (Horsburgh, vol. i. p. 214) ; it 
appears also encircled in Captain Owen’s chart of Mada- 
gascar ; coloured blue. — Great Comoro Island is, as I am 
informed by Dr. Allan, about 8,000 feet high, and ap- 
parently volcanic ; 1 it is not regularly encircled ; but reefs 
of various shapes and dimensions jut out from every head- 
land on the W., S., and S.E. coasts, inside of which reefs 
there are channels, often parallel with the shore, with deep 
water. On the N.W. coasts the reefs appear attached to 
the shore. The land near the coast is in some places bold, 
but generally speaking it is flat ; Horsburgh says (vol. i. 
p. 214), the water is profoundly deep close to the shore, 
from which expression I presume some parts are without 
reefs. From this description, I apprehend the reef belongs 
to the barrier class ; but I have not coloured it, as most of 
the charts which I have seen represent the reefs round it 
as very much less extensive than round the other islands 
of the group. 
Madagascar. — My information is chiefly derived from 
the published charts by Captain Owen, and the accounts 
given by him and by Lieut. Boteler. Commencing at the 
S.W. extremity of the island : towards the northern part of 
Star Bank (in lat. 25° S.) the coast for ten miles is fringed 
by a reef ; coloured red. The shore immediately S. of St. 
1 [Great Comoro is volcanic and about 8,600 feet high. There ia 
a little fringing-reef on the north and on the south-east side. — Lieut. 
Chas. Smith.] 
