6 THE MARINE BOTANIST. 



rarest, if we except Zonaria eollaris, a new addition 

 to our Flora, which has only lately been found by 

 Miss Turner, in Jersey. Twelve genera are com- 

 prehended in this tribe ; the succeeding one, Chor- 

 dariacese, contains but half that number : the fronds 

 in these plants consist of articulated filaments more 

 or less combined together : in Chordaria and Me- 

 sogloia, the frond is cylindrical, and branched ^ 

 tuber-like, in Leathesia; orbicular, with a dense 

 structure, in Ralfsia : the genera Elachista and 

 Myrionema consist of parasitical species ; the former 

 composed of free articulated filaments, rising 

 from a cartilaginous base : the members of this 

 genus are mostly parasites on particular species of 

 the Fucaceae : the Myrionema are found on various 

 algee, occurring in patches on their fi'onds, and 

 composed of erect, simple filaments, springing 

 from a thin expansion of filaments cohering to- 

 gether; in structure these two genera show an 

 approach to the Ectocarpacese 5 but their fruc- 

 tijication manifests a close resemblance with 

 Leathesia, which will not allow of their being re- 



