THE MARINE BOTANIST. 79 



half-tide level. The parasite is so much the colour 

 of the crust, that it requires a microscope to detect 

 it." Appin, Argyleshire. — '^ On stones covered with 

 IT. ruhra, at Falmouth, not uncommon." — Mr, W. 

 P. Cochs. 



ECTOCARPACE^.— ECTOCARPUS TRIBE. 



Articulate dark or olive-gTcen coloured sea- 

 weeds; with filiform, slender fronds, cartilaginous 

 or flaccid, not very juicy. '^ The spores are 

 (g-enerally) external, attached to the jointed 

 ramuli." 



From others of the olive sea-weeds, the plants 

 of this trihe are easily known by their jointed 

 fronds. Owing to the difiorent structure of these 

 articulations in the Sphacelaria and Ectocarpi each 

 are arranged in two small sub-divisions, named 

 respectively Sphacelarieae and Ectocarpese ; in the 

 former each articulation consists of several cells 

 surrounding the central portion j in the latter they 

 are composed of simple cells joined end to end; 



