VALKERIA. 371 



A good description of this interesting and beautiful zoo- 

 phyte is given by Professor Fleming, by whom the genus 

 was named in honour of the late Dr. Walker, Professor of 

 Natural History in the University of Edinburgh. The 

 stems usually arise from the base, filiform, jointed, and sup- 

 port the branches and cells bifariously : the cells are oval 

 and large ; often they occur in whorls in the axillae of the 

 branches; the polypi extend beyond the margin; tentacula 

 with hairs, which, by their motions, cause the water to 

 ascend in a current on one side and descend on the other, 

 acting, as is supposed, as aerating organs." This is got in 

 great beauty, and at times in considerable abundance, on 

 the coast of Ayrshire.. Dr. Fleming states that it is seldom 

 above two inches in height, but on Halidrys siliquosa we 

 have occasionally seen it four inches. Halidrys is its fa- 

 vourite ; but it is often found on Rhodymenia bifida, though 

 of smaller size than when on Halidrys. It is of a pale 

 yellowish colour, and makes a handsome specimen on paper, 

 to which it firmly adheres. I find that it is phosphorescent 

 when shaken in the dark. 



2. VALKERIA TJVA, Grape Coralline, Ellis. 



Hab. Leith, Jameson ; county Down, Templeton ; Couch, 

 Cornwall ; Dublin Bay, Hassall. 



