300 BULLETIN OF THE 



formiug, iu fact, the outline of a large island, which would include the 

 whole of the Virgin Islands, the whole of Porto Rico, and extend some 

 way into the Moua Passage. The 100-fathom line similarly forms a 

 large plateau, uniting Anguilla, St. Martin, and St. Bartholomew. It 

 also unites Barbuda and Antigua, forms the Saba Bank, unites St. 

 Eustatius, St. Christopher, Nevis, and Redonda. It forms an elongated 

 plateau, extending from Bequia to the southwest of Grenada, and runs 

 more or less parallel to the South American coast from the Margarita 

 Islands, leaving a comparatively narrow channel between it and the 

 100-fathom line south of Grenada, so as to enclose Trinidad and Tobago 

 within its limits, and runs off to the southeast in a direction also about 

 parallel to the shore line. At the western end of the Caribbean Sea 

 the 100-fathom line forms a gigantic bank off the Mosquito coast, ex- 

 tending over one third the distance from the mainland to the island of 

 Jamaica. The Rosalind and Pedro Banks, formed by the same line, and 

 a few other smaller banks, denote the position of more or less important 

 islands which must have once existed between the Mosquito coast and 

 Jamaica. On examining the 500-fathom line, we thus find that Jamaica 

 is only the northern spit of a gigantic i^i-omontory, which once extended 

 toward Hayti from the mainland, reaching from Costa Rica to the 

 northern part of the Mosquito coast, and leaving but a comparatively 

 narrow passage between it and the 500-fathom line encircling Hayti, 

 Porto Rico, and the Virgin Islands, in one gigantic island. The pas- 

 sage between Cuba and Jamaica has a depth of 3,000 fathoms, and that 

 between Hayti and Cuba is not less than 873 fathoms, the latter 

 being probably an arm of the Atlantic. The 500-fathom line connects, 

 as a gigantic island, the banks uniting Anguilla to St. Bartholomew, 

 Saba Bank, the one connecting St. Eustatius to Nevis, Barbuda to 

 Antigua, and from thence extends south so as to include Guadeloupe, 

 Marie-Galante, and Dominica, This 500-fathom line thus fonns one 

 gigantic island of the northern islands, extending from Saba Bank to 

 Santa Cruz, and leaving but a narrow channel between it and the 

 eastern end of the 500-fathom line inanning round Santa Cruz. As 

 Santa Cruz is separated from St. Thomas by a channel of forty miles, 

 with a maximum depth of over 2400 fathoms, this plainly shows its con- 

 nection with the northern islands of the Caribbean group, rather than 

 with St. Thomas, as is also well shown by the geographical relations of 

 its Mollusca. The 500-fathom line again unites, in one gigantic spit 

 extending northerly from the mouth of the Orinoco, all the islands to 

 the south of Martinique, leaving Barbadoes to the east, and a narrow 

 passage between Martinique and tlie islands of Dominica and St. Lucia. 



