APPENDIX. 259 



banks and "cays" further eastward on the southern side of 

 Cuba ; within them there is a large expanse, with a muddy 

 bottom, from eight to twelve fathoms deep; although some 

 parts of 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 

 Capt. 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 15 miles from the coast. 

 The islets on it are all low, as I have been informed by 

 Capt. 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 increases to 10 fathoms, and 

 within the northernmost part, for a space of 20 miles, the 

 depth is only from one to 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 

 penetrates the mainland to the depth of 50 miles; and 

 secondly, that considerable spaces of this barrier-like reef 

 are described in the charts (for instance, in lat. 16 45' and 

 16 12') as formed of pure sand; and thirdly, from knowing 

 that sediment 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, without further evidence 

 that it has really been formed by the growth of corals, and 

 that it is not merely in parts a spit of sand, and in other 



