108 BRITISH SEA-WEEDS. 



or two or three together ; stem rigid, erect, as thick as small 

 whipcord, or less, undivided and without branches below, 

 much branched and bushy above ; branches more or less 

 irregularly divided, tapering abruptly at the base, and gra- 

 dually at the tip ; branchlets narrow-spindle-shaped, taper- 

 ing towards either extremity, tipped with short fibrils, not 

 numerous on young plants, falling off in winter, and re- 

 appearing in much greater luxuriance in the succeeding 

 spring and summer ; articulations of the stem and branches 

 shorter than broad, partially hidden by the small cells which 

 surround the tubes; those of the branchlets as long as, 

 or longer than broad, and more distinctly visible. Spores 

 in egg-shaped, stalkless conceptacles ; tetraspores large, in 

 swollen branchlets. 



This species is perennial, and very common in most 

 localities at all times of the year. It grows on rocks, 

 shells, and pebbles, in tide-pools and in deep water. 

 Specimens in the first season of their growth differ much 

 from those in the second, and both change considerably 

 as winter approaches. The slender branchlets fall off, 

 like the leaves of a tree or land plant, and the stems 

 and branches are left bare until the ensuing spring. It 

 is from the appearance which it presents in this latter 

 state that the English name of Lobster-horn is derived. 



Polysiphonia violacea. The Violet Poly- 

 siphonia. 



Fronds from a few inches to a foot long, of a brownish- 

 red colour, becoming violet when dry; stem varying in 

 thickness according to the size of the plant, irregularly 

 divided, becoming broad and flat when laid out on paper ; 

 branches alternate, long, silky; branchlets very slender, 

 tufted, tipped with fibres ; articulations of the stem and 



