SEA WEEDS 



361 



FIG. 247. Griffithsia 

 corallina 



somewhat like Setacea, but is larger, and the tips of its branches are 

 obtuse. Its fronds grow in fan-shaped tufts five or six inches long. 

 It is not a common weed, but may often be met with on the coast 

 of Devon and Cornwall. 



O. barbata, or the Bearded Griffithsia, receives its name from 

 its very delicate fibres, which bear spherical, pink tetraspores. It 

 seems to occur only on the south and south-west coasts, where it 

 grows on stones or attached to other weeds. 

 Our last example of the genus is G. corattina, 

 which is of a deep-crimson colour, and is so 

 jointed as to have the appearance of a coral- 

 line. Its fronds are from three to eight 

 inches long, regularly forked, and of a gela- 

 tinous nature. The joints are somewhat 

 pear-shaped, and the spore clusters are 

 attached to their upper ends. It soon fades, 

 and even if its colour is satisfactorily pre- 

 served, the pressure of the drying press 

 destroys the beautiful rounded form of its 



bead-like joints. It forms a lovely permanent specimen, however, 

 when preserved in a bottle of salt water, with the addition of a 

 single grain of corrosive sublimate. 



Our next genus (Halurus) contains a common weed of the south 

 coast which was once included in Griffithsia. It is the Equisetum- 

 leaved Halurus (H. equiseti- 

 folius), so called because 

 its. branches are regularly 

 whorled round the nodes of 

 the jointed branches, thus 

 resembling the semi-aquatic 

 Mare's Tail. Its frond is tu- 

 bular, and the spore-clusters 

 are situated on the tips of 

 the branches, surrounded by 

 a whorl of small branchlets. 



The genus Pilota has a 

 slightly flattened cartilagi- 

 nous frond, divided pinnately, and the axis surrounded by a cuticle 

 of two layers of cells. The spore-clusters, at the tips of the branches, 

 are surrounded by a whorl of branchlets. It contains only two 

 British species, one of which (P . plumosa) is a very feathery species, 



FIG. 248. Halurus 

 equisetifolius 



FIG. 249. Pilota 

 plumosa 



