104 BRITISH SEA-WEEDS. 



Polysiphonia formosa. The beautiful Polysiphonia. 



Fronds densely tufted, from six to ten inches long, erect, 

 very slender, divided into long, nexuose branches and branch- 

 lets, whose tips are sometimes iibrillose ; articulations 

 mostly many times longer than broad. Spores in pitcher- 

 shaped, stalked conceptacles ; tetraspores in single rows, in 

 spindle-shaped branchlets. 



Although by no means common, this species is distri- 

 buted over the coast of the British Isles from Shetland 

 to the south of England. It grows on rocks near 

 low-water mark, chiefly in bays and estuaries, and is 

 considered by some writers to be only a very slender 

 form of P. urceolata, from which species it differs in 

 the much greater delicacy of its fronds, and the longer 

 articulations of its stems. It is annual, and grows in 

 summer. 



Polysiphonia fibrata. The fibred Polysiphonia. 



Fronds growing in very dense tufts, from two to eight 

 inches long, as thick as a bristle at the base, tapering up- 

 wards, erect, gelatinous, of a dark red colour ; branches 

 dichotomous ; branchlets tipped with tufts of jointed fibres ; 

 articulations mostly several times longer than broad. Spores 

 in ovate, wide-mouthed, stalked conceptacles ; tetraspores 

 small, in distorted branchlets. 



This is another widely distributed species. It is annual, 

 and grows, during summer and autumn, on rocks and 

 algae in tide-pools near low-water mark, and occasionally 

 in more exposed places. The fibres at the tips of its 

 branches, from which the name fibrata is taken, although 

 not peculiar to it, for most Polysiphonia have them in 

 certain stages of their growth, are more constant and 



