Plate LIII. 



Fig. 242. CERAMIUM RUBRUM. 



Colour. Sometimes clear red, sometimes darker; brownish-yellow and white in decay; 

 on examination, of different shades. 



Suhstanee. Firm when fresh; soon turning flabby; giving out a pleasant smell. 



Character of Frond. Tufts of jointed threads {filaments). Filaments sometimes 

 coarse, sometimes slender; becoming finer upwards from the base; much and 

 irregularly branched in a partly forked, partly alternate manner; set throughout 

 more or less with once-forked, or many-times-divided, often secund branchlets. 

 Tips hooked in. 



Joints. Coloured throug^hout red, but in different shades. Darkest at, and near, the 

 partition-lines {dissepiments'), which are always slightly contracted, and in 

 drying often shrink considerably. 



Measurement. From 2 to 12 inches long. 



Fructification. Of two kinds. 1. Minute spores in globose capsules, with two or 

 three short, curved branchletee^z-? underneath; mostly borne on the side- 

 branchlets. 2. Tetraspores set round the joints. 



Habitat. Our coasts generally. In pools from high to low-water mark, and beyond. 

 Very common. 



No description can include all the varieties of this most variable plant, but 

 whether dark or pale, bright or dingy, it is coloured throughout, though in 

 shades; and as there is but one other un-tliorned British Ceramium {G. hotryo- 

 carpum) in which this is the case, the detection of delusive varieties is not so 

 difficult as may be thought. From C. hotryocarpum it differs entirely in its 

 capsular fruit. 



Fig. 243. CERAMIUM BOTRYOCARPUM. 



Colour. A dull purplish-red, fading to green and yellow; on examination, of different 

 shades. 



Substance. Rigid. 



Character of Frond. Tufts of jointed threads {filaments). Filaments crooked at the 

 base; rather coarse; becoming gradually finer upwards; much and irregularly 

 branched; in a sometimes forked, sometimes alternate manner; closely set with 

 numerous short, simple, or once or twice divided branchlets. Tips straight. 



Joints. Coloured throughout dull purplish-red, but in different shades. Darkest at, 

 and near, the partition-lines {dissepiments), which are always slightly con- 

 tracted, and in drying shrink considerably. 



Measurement. From 2 to 6 inches long. 



Fructification. Of two kinds, but only one thoroughly made out. Tetraspores set 

 round the joints. The other consists of minute dark fruit-warts heaped 

 together in roundish clusters; sessile on the branchlets. Occasionally a true 

 capsule, with two or three branchletee^zs underneath, has been met with. 



Habitat. Our coasts generally. On rocks, &c. between tide-marks. Common. 



Besides the clumsy and unusual fruit, this plant is darker than (7. ruhrum, 

 and more purple. Moreover, the tips of all the branchlets are straight, instead 

 of hooked in. 



31 



