XX INTRODUCTION. 



Gulf Stream, to a distance of about 120 miles to the eastward 

 of Charleston. Finding that our depth did not increase at that 

 distance, — our greatest depth not being much more than 350 

 fathoms, — Commander Bartlett thought it prudent to return 

 towards shore, to the so-called axis of the Gulf Stream, and to 

 run a line in a northeastern direction parallel to the coast in the 

 trough of the Gulf Stream. To our great astonishment the 

 depth still did not increase, and we carried from 250 to less than 

 300 fathoms until we reached nearly the latitude of Cape Hat- 

 teras, when in a short distance there was a very rapid drop from 

 352 fathoms to 1,386 fathoms. A fifth line was run normal to 

 this northern slope of the Gulf Stream plateau, to a depth of 

 1,632 fathoms. A sixth line was run to the northward of Cape 

 Hatteras, to a depth of 1,047 fathoms. A seventh line was run 

 east, off Cape May, from the hundred-fathom line to 1,200 

 fathoms. 



In accordance with an arrangement made with the late Sir 

 Wyville Thomson, by which the collections made by American 

 and English deep-sea expeditions were to be sent to the same 

 specialists, the collections of the " Blake " were worked up 

 under the most favorable conditions. But as the greater part 

 of the collections made during the third cruise of the " Blake " 

 cover the extension into deep water of the ground already in 

 part occupied by the United States Fish Commission, the col- 

 lections made north of Cape Hatteras were sent to the natural- 

 ists to whom the collections of the Fish Commission had been 

 intrusted. 



In the preparation of the final Reports published upon the 

 " Blake " collections, the special knowledge of those who have 

 carefully followed the development of a limited grou^) of inver- 

 tebrates, their palseontological and geographical distribution, 

 their migrations, and the causes which have probably led to the 

 existing condition of things from a former geological period, 

 has been indispensable. I cannot adequately express my thanks 

 to the gentlemen who have so kindly undertaken the laborious 

 task of preparing the Reports of the " Blake " collections. 

 Without their assistance, the work would have been neither 

 prompt nor satisfactory. 



