INTRODUCTION. xi 
While at the Tortugas we were allowed by the Secretary of 
War to occupy such quarters at Fort Jefferson as were not oth- 
erwise needed, and we selected as a laboratory a large room, 
with excellent light, on the ground floor of the barracks. On 
days when the weather was not suitable for surface work out- 
side in the Gulf Stream, I employed the launch in cruising 
inside the reef, and thus examined carefully the topography of 
the different groups of corals characteristic of the Florida reefs. 
The results of this visit, as well as those made on previous occa- 
sions, have enabled me to give a somewhat extended account of 
the Florida reefs in a special chapter of this book. We re- 
mained at the Tortugas five weeks, and returned to Key West 
in the revenue steamer * Dix," Captain Seammon, whom the 
Secretary of the Treasury had authorized to assist us as far as 
practicable. At Key West we occupied as a work-room the 
loft of the Navy Depot building, and continued our studies of 
the pelagie fauna of the Gulf Stream. 
During the second dredging season (1878-79), the “ Blake” 
was in charge of Commander J. R. Bartlett, U. S. N. The cruise 
extended from Washington to Key West, from Key West to Ha- 
vana, from Havana to Jamaica through the Old Bahama Chan- 
nel and Windward Passage, from Jamaica to St. Thomas along 
the south coast of Hayti and Porto Rico. From St. Thomas 
the “Blake ” visited Santa Cruz, Saba Bank, Montserrat, St. 
Kitts, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vin- 
cent, the Grenadines, and Grenada ; she also carried the dredg- 
ings south as far as the hundred-fathom line off Trinidad, 
returned to St. Vincent, and finished the dredging operations 
at Barbados. 
On November 27, 1878, I joined the “ Blake” at Washing- 
ton for a second dredging cruise. We intended to proceed to 
Nassau, and there devote a few days to dredging and sounding, 
in order to trace the connection between the fauna of the north- 
ern extremity of the Bahama Banks and that of the Straits of 
Florida. On account of rough weather this was not deemed 
prudent, and we were compelled to put into St. Helena Sound ; 
and, for the same reason, when off Jupiter Inlet, instead of 
crossing the Gulf Stream to make Nassau, it was thought best 
