SEA WEEDS 365 



like, irregularly branched, and of a purplish-red colour. The 

 spores are contained in external tubercles, and the tetraspores 

 are arranged in masses beneath the surface. The only common 

 species is G. mamillosa, which has a linear, furrowed stem, with 

 fan-shaped, deeply-cleft fronds. The spores are contained in 

 mamilliform tubercles scattered over the surface of the frond. 



Callophyllis (Rliodymenia) laciniata is found on most rocky 

 coasts. It has bright-red, fleshy fronds that are deeply cleft into 

 wedge-shaped segments, the fertile specimens with 'waved edges 

 and small marginal leaflets. It is found on rocks and Laminaria 

 stems beyond the tide-marks, but is commonly washed up on the 

 beach during storms. It is a beautiful weed, and retains its colour 

 well when dried. 



Cystoclonium (Hypnted) purpurascens is a very common weed, 

 growing on other algae between the tide-marks, and sometimes 

 reaching a length of two feet. Its cartilaginous, purple fronds are 

 much branched, and become almost black when dried. The spores 

 are embedded in the smallest branches, and the tetraspores are 

 arranged among the superficial cells. 



The genus Phyllophora contains a few British weeds with a 

 stiff, membranous frond, bearing leaf-like appendages, and supported 

 on a stalk. The tetraspores are contained in external wart-like 

 swellings. The commonest species is P. membrcmifolia, the fronds 

 of which are divided into wedge-shaped segments, and grow in tufts 

 from an expanding root. The spores are contained in stalked 

 sporangia, and the tetraspores are near the centres of the segments. 

 Another species P. rubens has a shorter stem, and grows in deep 

 and shady rock pools. Its fronds are densely tufted ; and, as the 

 plant grows, new series of segments are formed at the tips of the 

 older ones. A third species (P. palmettoides) has a very bright-red 

 frond and an expanded root. 



The order Rhodymeniacece includes a number of red or purple 

 sea weeds with flat or thread-like unjointed, cellular fronds, the 

 surface cells forming a continuous coating. The spores are lodged 

 in external conceptacles, and are at first arranged in beaded threads. 

 The tetraspores are either distributed among the surface cells, 

 collected in clusters, or situated in special leaflets. 



The typical genus (Rhodymenia) contains two red, membranous 

 weeds, the commoner of which is E, palmata (Plate VIII.),so com- 

 mon on the Scottish and Irish coasts, where it forms an important 

 article of diet, and is known as the Dulse or Dillisk. It is also 



