THE PELAGIC FAUNA AND FLORA. 211 
of yellowish green or golden olive, reaching over the dark bluc 
water of the Atlantic. 
The “Challenger” sailed round this so-called Sargasso Sea, 
but nowhere encountered it in sufficient quantities to become 
an impediment to navigation. We meet with this gulf-weed 
everywhere in the Gulf of Mexico, but scattered and only in 
small patches, and to the leeward of the Windward Islands. 
It is very abundant in the old Bahama Channel, and mod- 
erately common all along the course of the Gulf Stream from 
off Charleston to Cape Hatteras. The largest mass of gulf- 
weed I have encountered was in making the passage from 
St. Thomas to Havana. While steaming within sight of the 
northern shores of Porto Rico and of San Domingo, we were 
never out of sight of immense accumulations of gulf-weed, parts 
of which rose a few inches above the water, the whole forming 
long trains which trailed with the winds and currents. The 
weed became less and less common as we approached the old 
Bahama Channel. But these masses of Sargassum were of 
slight thickness, and were mere floating patehes, more or less 
entangled. 
The numerous young and tender leaves found on every stem 
show that the weed is in a most flourishing condition, and is 
not merely dead weed floating about in the great vortex of oce- 
anie circulation. It is not known what becomes of the gulf- 
weed annually driven by the equatorial current through the 
passages of the West India Islands into the Caribbean. The 
bulk of the weed which passes through the Windward Passage 
probably finds its way through the Yucatan Channel and the 
Straits of Florida into the Gulf Stream proper, but its final fate 
is not known. The amount of gulf-weed met with north of 
Cape Hatteras in the track of the Gulf Stream is small ; it grad- 
ually increases as one goes south. 
One of the objects of the “Talisman” expedition was to 
investigate the Sargasso Sea. The French explorers “ nowhere 
met the enormous masses of floating Sargassum, which the old 
navigators compared to floating prairies." While sailing, the 
1 Commander Bartlett found large masses of gulf-weed on the southern edge of 
the Gulf. Stream. 
