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APPENDIX. 
within them there is a large expanse, with a muddy bottom, 
from 8 to 12 fathoms deep : although some parts on this 
line of coast are represented in the general charts of the 
West Indies, as fringed, I have not thought it prudent to 
colour them. The remaining portion of the south coast of 
Cuba appears to be without coral-reefs. 
Yucutan. — The N.E. part of the promontory appears, 
in Captain Owen’s charts, to be fringed ; coloured red. 
The eastern coast from 20° to 18° is fringed. South of lat. 
18°, there commences the most remarkable reef in the 
West Indies : it is about 130 miles in length, ranging in a 
N. and S. line, at an average distance of fifteen miles from 
the coast. The islets on it are all low, as I have been in- 
formed by Captain B. Allen ; the water deepens suddenly on 
the outside of the reef, but not more abruptly than off many 
of the sedimentary banks : within its southern extremity 
(off Honduras) the depth is 25 fathoms ; but in the more 
northern parts, the depth soon decreases to 10 fathoms, and 
within the northernmost part, for a space of 20 miles, the 
depth is only from one or two fathoms. In most of these 
respects we have the characteristics of a barrier-reef ; never- 
theless, from observing, first, that the channel within the 
reef is a continuation of a great irregular bay, which pene- 
trates the mainland to the depth of 50 miles ; and secondly, 
that considerable spaces of this barrier-like reef (for instance, 
hi lat. 16° 45' and 1G° 12') are described in the charts as 
formed of pure sand ; and thirdly, from knowing that sedi- 
ment is accumulating in many parts of the West Indies in 
banks parallel to the shore ; I have not ventured to colour 
this reef as a barrier. To add to my doubts, close outside 
this barrier-like reef, Turneffe, Lighthouse, and Glover reefs 
are situated, and these have so completely the form of atolls, 
that if they had occurred in the Pacific, I should not have 
hesitated to colour them blue. Turneffe Beef seems almost 
entirely filled up with low mud islets ; and the depth within 
