Mg. 275. CALLITHAMNION THUYOIDEUM. 



Colour. A fine rose-red. Suhstance. Soft and limp. 



Character of Frond. Tufts (or single plants) of very five, jointed threads {filaments)^ 

 very much branched. Stems exceedingly slender; nearly simple below, set above 

 with alternate branches. These once or twice re-branched. The lesser ones, and 

 sometimes all, clothed with branchlets, which are beautifully plumed and re- 

 plumed with one, two, or even three sets of gradually-diminishing branchleteews. 

 The whole branching at one level, as if cut out. Outline of the plumed branches 

 very narrow oblong. 



Joints. Visible throughout. 



Measureme7it. One or 2 inches long. 



Fructrficatmi. Of two kinds. 1. Minute spores in large oval capsules; generally sessile 

 on the sides (not at the tips) of the branchlets; very rare. 2. Globose tetra- 

 spores borne on the tips of the (then) shortened branclileteews. 



Habitat. Our coasts occasionally. Yarmouth, Plymouth, &c. On rocks near low- 

 water mark. Rare. 



Fig. 276. CALLITHAMNION CORYMBOSUM. 



Colour. A pink or purplish-red. 



Substance. Exceedingly soft, limp, and gelatinous; having a fine gloss when dried. 



Character of Frond. Thread-like {^filamentous^ \ jointed; excessively branched. Stem 

 hair-like below; cobweb-fine above (occasionally much more robust); closely set 

 with long, alternate branches. Branches partly divided in a forked manner; 

 partly alternate; re-branched in a similar way. The last series clothed with 

 very compound, alternate branchlets. Branchlets zigzag; set at every joint 

 with cobweb-fine, repeatedly-forked branchlet^^ws, of nearly uniform length; 

 each tip, therefore, forming a roundish outline, something like those of C. 

 spongiosum; but not so bushy. 



Joints. Visible throughout; even in the stems. 



Measurement. From 1 to 3 inches long. 



Fructification. Of two kinds. 1. Minute spores in large, double capsules; sessile in 

 the angles of branching {axils). 2. Minute, round tetraspores, a single one 

 sessile on one side of the forked hr'AwoiAeteens, immediately below the point 

 where they fork. 



Habitat. South and West of England. West of Scotland. Isle of Man. Ireland 

 generally. On rocks, algae, and Zostera marina near low-water mark. Not 

 uncommon. 



Fig. 277. CALLITHAMNION FLORIDULUM. 



Colour. A purplish-pink. Substance. Soft and almost spongy. 



Character ofi Fro7id. Dense tufts of fine, jointed threads {filaments), forming a 

 roundish cushion on the rocks. Filaments equally slender throughout; once 

 or twice forked; furnished with a few long, simple or forked, very upright 

 branches; the upper ones sometimes clothed near the top with a few secund 

 or alternate, upright bi"anchlets (the lowermost longest), on which the tetra- 

 spores are borne. 



Joints. Visible throughout under the microscope, or even through a pocket lens, 

 having a peculiar shimmery appearance, from the silvery whiteness of the 

 cell-membrane. 



Measurement. About an inch high. 



Fructification. Only one kind known. Minute, oval tetraspores, borne on very short, 

 upright branchlets (or stalks), ranged in a secund manner along the upper 

 branches. 



Habitat. West of Ireland. Orkney. Land's End. Scilly. Isle of Man. On sand- 

 covered rocks near low-water mark. Not uncommon. 



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