THE MARINE BOTANIST. Ill 



three or four inches hig-h. Cylindrical^ branches with 

 rounded axils. Colour, a dull brown, or brownish- 

 yellow. 



jB. fruticulosa. Grows between tide-marks on 

 sand- covered rocks. Perennial. Summer. Com- 

 mon. Fronds three to six inches high, much 

 branched from the base ] axils of the branches very 

 patent. Articulations very obvious in the ramuli, 

 and marked with transverse striae. Antheridia in 

 this and the preceding* kind constantly occur in 

 summer, and give a yellowish tinge to the plants. 



POLYSIPHONIA. 



Name signifying many-tuhed, in allusion to the structure of 

 the frond. 



Frond filamentous, partially or generally arti- 

 culate, joints longitudinally striate, composed inter- 

 nally of parallel tubes ranged round a central cavity. 

 Fructification double on distinct plants. 1. Cera- 

 midia containing pear-shaped spores. 2. Tetra- 

 spores imbedded in swollen branchlets. 



