THE MARINE BOTANIST. 247 



Bay. Dublin Bay. At Balbriggan, &c., " very 

 abundant."— Dr. W. H. Harvey. Frith of Forth. 

 Ardrossan. 



CERAMIUM DIAPHANUM. — LARGE, 

 TRANSPARENT-JOINTED CERAMIUM. 



From two to six inches high, irregularly forked, 

 branches set with lateral small forked ramuli ; arti- 

 culations pellucid, very evident, three or four times 

 as long as broad in the main stem, much closer in 

 the ramuli, dissepiments dark-coloured, swollen. 

 Tips of the ramuli hooked inwards. Favellae near 

 the tips of the branches, with involucral ramuH ; 

 tetraspores immersed, in whorls round the joints. 

 Dr. Harvey, in his remarks on this plant in the 

 Phycohgia Britannicay says : — " From the British 

 species of this section, except one, our (7. diaphanum 

 may be at once known by its larger size and more 

 robust filaments 5 it is also well characterized by the 

 lateral dichotomous ramuli given off all along the 

 principal divisions of the frond, and by the gradu- 



