210 THREE CRUISES OF THE “ BLAKE." 
This weed is not only pelagic, but is also found growing 
attached to rocks in the West Indies and along the Florida 
Fig. 136. — Gulf-Weed. 
si 
Reef, but no locality is known which could furnish the supply 
of gulf-weed necessary to form the floating masses in the Atlan- 
tic. How it has assumed its pelagic life is not known, but it 
undoubtedly forms extensive narrow strips, long irregular trains 
very slowly to 169 C. at that depth. Tt ! A Pacific species of Sargassum, which 
oceupies in the central part of the south- is occasionally found floating near the 
ern North Atlantic the position of the Sandwich Islands, grows quite abun- 
area of greatest density of sea-water, — dantly on the coral reefs of Oahu and 
over 1.027. Maui. 
