FUCACEiE. 39 



diate between these two genera, partaking of the charac- 

 ters of both. 



Cystoseira ericoides. Heath-like Cystoseira. 



Stem woody, short, with slender branches covered with 

 awl-shaped spines or leaves. Air-vessels solitary, small, 

 placed near the tops of the branches. Spore-receptacles 

 cylindrical, with awl-shaped points. 



The rock pools of the sonth and south-west coast of 

 England and Ireland abound with this plant, which is 

 also very plentiful in the Channel Islands. It is very 

 rare in the northern districts, and has scarcely ever been 

 found in Scotland. When seen growing under water it 

 is beautifully iridescent, and may be easily distinguished 

 by this character, which no allied species possesses. 



Cystoseira graxmlata. Granular Cystoseira. 



Stem covered with elliptical knobs, from which spring 

 slender, repeatedly divided branches. Air-vessels two or 

 three together. Spore-receptacles elongated. 



The distinctive character of this plant is the knotted 

 stems from which it takes its name. It is to be found 

 in similar situations to C. ericoides, and is common in 

 many localities. 



Cystoseira barbata. Bearded Cystoseira. 



Stem cylindrical, with small knobs bearing very slender, 

 much divided branches. Air-vessels lance-shaped, not always 

 present. Spore-receptacles small, with a bristle-like point. 



The claim of this plant to a place among our native 

 Sea-weeds is infinitesimally small, and the young collec- 

 tor need not, therefore, perplex himself by endeavouring 

 to find it among his slender specimens of C. yranulata, 



