116 THE MARINE BOTANIST. 



the equality of its short joints, and for its property 

 of resisting fresh water/' 



P. eloiigella, "This closely resembles small 

 specimens of P. elongata, but it is easily and clearly 

 distinguished by the distinctly jointed branches, and 

 the parallel (not reticulated) veins which they 

 contain." Grows on rocks, &c., between tide- 

 marks. Biennial. Spring. Eather rare; but ge- 

 nerally distributed round our shores. 



P. Grevillii, Shores of Bute, on the larger 

 algae, only a variety of the following : — 



P. violacea, A species not very unlike P. fibrata, 

 but differing from it in its inarticulate stem and 

 finer and larger growth. 



P. Carmichaeliana. Parasitical on DesmarestidT 

 aculeata at Appin. The single specimen of this 

 plant, found by Captain Carmichael, is preserved in 

 Sir W. J. Hooker's Herbarium. 



P.Jibrillosa. Grows on rocks and stones and 

 on algae between tide-marks. Annual. Summer. 

 Common. Substance very tender, and soon de- 

 composing. " Colour a pale starw, or some- 



