120 THREE CRUISES OF THE '"' BLAKE." 



the warm waters of the Gulf Stream. The belt is quite 

 narrow at Cape Hatteras, owing to the steepness of the conti- 

 nental slope at that point, and gradually increases in width 

 and depth as we go south along the trough of the Gulf 

 Stream, its greatest width being off the Carolina and Georgia 

 coasts. The marked influence of the currents on the fauna 

 of the district through which they flow is well illustrated by 

 the wholesale destruction of the tile fish and of several species 

 of Crustacea during the Avinter of 1881-82, as noted by Pro- 

 fessor Verrill, of the United States Fish Commission. This 

 was perhaps due, as he suggests, to the fact that a severe 

 storm forced the cold water of the shallow shore-belt out to sea, 

 and suddenly lowered the temperature of the narrow belt of 

 outlying warm water. This belt covers an area which is prob- 

 ably the northern limit of many species collected in abundance 

 during previous seasons. 



We were greatly surprised at the meagreness of the fauna on 

 the lines off Charleston and in the Gulf Stream. Owing partly 

 to the very gradual slope of the continent towards deep water, 

 and partly to the strong current of the Gulf Stream, which sweeps 

 everything off the bottom along its course, there is but little 

 food for the deep-water animals, and it was only along the edges 

 of the Gulf Stream where mud and silt had accumulated that 

 we made satisfactory hauls on our southern lines. What was 

 obtained seemed to be a scanty northern extension of the fauna 

 of the Caribbean Sea and of the Gulf of Mexico occurring 

 between the hundred and the three-hundred-and-fifty fathom 

 lines. It was not until we trawled on the steep slope of the 

 Gulf Stream plateau south of Cape Hatteras, where the bottom 

 was fine mud and globigerina ooze, that we made a rich harvest 

 again, in striking contrast to the poor hauls along the well- 

 swept rocky or hard bottom of the Gulf Stream to the south- 

 ward. Although pteropods were very common at the surface 

 all the way from Charleston to Cape Hatteras, they were only 

 rarely brought up dead from the bottom ; but when the steep 

 slope south of Hatteras was reached, they again assumed a 

 prominent part in the composition of the bottom mud. 



The effect of currents on the distribution of birds has been 



