36 



OlIVE-COIOURED SEA-WEEDS.-MELAKOSPERMEiE. 



ObdeeI. FUCACEiE. 



Fronds witJiout joints, mostly large and of tough leathery 

 texture. Spores in globular cavities, in the substance of the 

 frond. 



Genus I. SARGASSUM. 



Proud branched, with a distinct stem bearing leaves. 

 Air-vessels simple, on short stalks. Spore-receptacles small, 

 generally in axillary clusters. 



Upwards of one hundred species of this genus have 

 been described. They are distributed over the warmer 

 latitudes of both hemisphereSj and are especiallynumerous 

 in the Red Sea. The enormous masses of floating weed, 

 which exist in the tropical part of the Gulf Stream, are 

 composed of two or three species, chiefly of S. bacciferum. 

 The early navigators called the Gulfweed Sargazo, or 

 Sea-lentils, from the resemblance of its air-vessels, which 

 they doubtless mistook for seeds, to the pods of the 

 lentil. Hence the name of the genus. Two species are 

 usually considered to belong to the English marine flora ; 

 but they are certainly not natives, and their only claim 

 to be admitted is the fact that they have been occasion- 

 ally picked up on our coasts. 



Sargassum vulgare. Common Sea-lentils. 



Stem smooth, slender, alternately branched. Leaves ob- 



