210 



THREE CRUISEb 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. ^. 



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 16° C. at that depth. It ^ A Pacific species of Sargassum, which 



occupies in the central part of the south- is occasionally found floating near the 



em North Atlantic the position of the Sandwich Islands, grows quite abun- 



area of greatest density of sea-water, — dautly on the coral reefs of Oahu and 



over 1.027. Maui. 



