MUSEUM OF COMPARATIVE ZOOLOGY. 301 



At the time of this connection, therefore, the Caribbean Sea connected 

 with tlie Atlantic only by a nan-ow passage of a few miles in width 

 between St. Lucia and Martinique, and one somewhat wider and slightly 

 deeper between Martinique and Dominica, another between Sombrero 

 and the Virgin Islands, and a comparatively narrow passage between 

 Jamaica and Hayti. The Caribbean Sea, therefore, must have been 

 a gulf of the Pacific, or have connected with it through wide passages, 

 of which we find the traces in the Tertiary and Cretaceous deposits of 

 the Isthmus of Darien, of Panama, and of Nicaragua. Central America 

 and northern South America at that time must have been a series of 

 large islands with passages between them from the Pacific into the Carib- 

 bean. It is farther interesting to speculate what must have become of 

 the great equatorial current, or rather of the current produced by the 

 northeast trades. The water banking up against the two large islands, 

 then forming the Caribbean Islands, must, of course, have been deflected 

 north, have swept round the northern shores of the Virgin Islands, 

 Porto Rico, and Hayti, and poured into the western basin of the Carib- 

 bean Sea, through the passage between Hayti and Cuba. This water 

 being forced into a sort of funnel, by the 500-fathom line forming the 

 southern line of the Great Bahama Island, which connected nearly the 

 whole of the Bahamas with Cuba and formed a barrier to the western 

 flow of the equatorial current, this must, therefore, for the greater part, 

 have been deflected north, and either swept in a northeasterly direction, 

 as the Gulf Stream now does, or round the north end of the Bahamas, 

 across Florida, which did not then exist, across the Gulf of Mexico, and 

 into the Pacific over the Isthmus of Tehuantepec. To Commander 

 Bartlett's interest in this subject I am indebted for the first infoi*mation 

 respecting the lines run between the islands : — 



Extract from Letter of Commander J. R. Bartlett, U. S. N. 



*•' I connected the islands by running traverses across the ridges. From St. 

 Vincent to St. Lucia the ridge was only from 150 to 170 fathoms below the 

 surface, with a channel of 400 fathoms near St. Vincent. The channel be- 

 tween St. Lucia and Martinique had 500 fathoms in mid-channel, sloping 

 upward to each isLind. The channel between Martinique and Dominica was 

 a tough one, and I thought I should never find, a ridge. The soundings in- 

 creased regularly on a ridge to 300 fathoms in mid-channel, where I got a 

 sounding of 883 fathoms, and then 1,000 fathoms ; beyond this the ridge was 

 some ten miles to the westward, Avilh an average depth of 400 fathoms, but I 

 found two peaks with only 40 fixthonis. The deep water from the Caribbean 

 Sea makes in between Guadeloupe and Montserrat, but I found a ridge of about 

 300 fathoms connecting Antigua with -Guadeloupe. In this channel I also 

 found a peak with only forty fathoms. I finished up the line connecting Saba 



