The studies which have given to the world so much information concerning the continental shelf surrounding the main body of North America have been continued, or, perhaps more properly, were initiated, in the West Indian waters. For this important work we are indebted mainly to the United States Coast and Geodetic Survey and the United States Fish Commission. The work of officers of the United States Navy in charge of Coast Survey and Fish Commission vessels, in making accurate measurements of depths, temperatures, strength and direction of currents, character of bottom, etc., has, in some instances, been commemorated on maps of the sea-floor by such names as Brownson Deep, Sigsbee Deep, Bartlett Deep, etc. The routine survey work referred to has been supplemented and extended by the labours of Louis Agassiz, L. F. Pourtales, Alexander Agassiz, and others in studying the life in the sea, the origin and history of the material forming the sea-bottom, and the nature of the shelves, banks, deeps, etc., which give diversity to its topography. The continental shelf bordering Florida on the east is separated from a similar submarine embankment surrounding the Bahama Islands by a channel 56 miles wide and from 200 to 500 fathoms deep (Fig. 3). This channel when followed northward becomes shallower and broader, and opposite the Carolina coast is no longer discernible in the relief of the broad continental shelf. The Gulf Stream flows northward through this Florida channel, as it is termed, with a current of from 2 to 6 miles per hour. These conditions are such as to suggest that the channel referred to has in part been excavated by the Gulf Stream. [Illustration: FIG. 3.--Gulf of Mexico and the Caribbean region: topography of sea-floor. The first contour line from the land indicates a depth of 600 feet--the outer margin of the continental shelf. Contour interval below the 600-foot curve, 3,000 feet. After R. T. Hill.]