THE MARINE BOTANIST. 243 



containing* minute spores ; 2. tetraspores either 

 immersed in the ramuli, or more or less external. 



Section 1. — Rubra. Smooth; the whole surface 

 of the articulation covered with coloured cells. 



CERAMIUM RUBRUM.— RED CERAMIUM. 



Frond from two to twelve inches high, very 

 variable in its branching, irregularly forked, with 

 many or few side ramuli which are either secund 

 or forked. Favellae mostly on the side branchlets, 

 set round with three or four ramuli. Tetraspores 

 immersed in the articulations. This is one of the 

 most puzzling plants to the young botanist, varying 

 as it does so greatly in ramification and colour ; 

 its natural hue is a clear red, but in shallow 

 pools near high water-mark it is often brownish or 

 yellowish. Very frequent on our shores, growing 

 on stones and algse in tide-pools, and in four to five 

 fathoms water. Annual. Summer and Autumn. 



