THE MARINE BOTANIST. y 



GENERA OF THE FUCUS TRIBE. 



Halidrys, Air-vessels stalked^ long-^ pod-shaped. 



Cystoseira, Air-vessels in the branches. Recep- 

 tacles small. 



Pycnophycus, Root composed of branching* fibres. 

 Receptacles cellular. 



Fucus, Root a round or flattened disk. Recep- 

 tacles large, filled with mucus traversed by 

 jointed threads. 



Himanthalia, Frond round, small, and cup- 

 shaped. Receptacles resembling* fronds, very 

 long, and repeatedly forked. 



HALIDRYS. 



Name signifying sea-oak. 

 Frond compressed, coriaceous, linear, pinnated 

 with distichous branches. Air-vessels lanceolate, 

 stalked, divided internally into several cells by 

 transverse partitions. Meceptacles lanceolate, ter- 

 minal, stalked, the surface pierced by pores which 

 communicate with internal spore-cavities. 



