Fig. 121. POLYSIPHONIA NIGKESCENS. 
Colour, A dull brown, sometimes a purplish red ; old plants becoming black ; all, darker in 
drying. 
Substance. Eigid below ; soft and delicate above. 
Character of Frond. Long tufts of jointed threads (^filaments')., very much and variously 
branched. Stems robust, nearly simple ; sometimes set throughout with richly 
feathered branches. In autumn and winter rough below with broken remains ; 
bushy above. Branches long, alternate ; repeatedly re-branched in a feather -like 
manner (^pinnate) ; the sets becoming gradually more and more slender. Branchlets 
short, alternate, distant, below ; the uppermost often crowded together ; mostly simple, 
awl-shaped. Joints closely marked with numerous upright lines (internal tubes). 
Internal Tubes. From twelve to twenty. 
Measurement. From 6 to 8 inches long. 
Fructification, Of two kinds. 1. Clustered spores in broadly ovate, unstalked capsides, with 
a narrow opening ; external. 2. Tetraspores immersed in the lesser branchlets. 
Habitat, All round our coasts. On rocks, stones, and alg8e between tide-marks. Very common. 
Summer specimens are feathery and beautiful; autumn and winter ones coarse and 
bushy. But, independently of this, it is one of the most variable of sea-weeds. Dr. Harvey 
considers its “ distantly pinnate” branchlets, and the great number of its tubes sufficiently 
characteristic marks, but he has recorded seven American varieties, and Britain could add 
more. In one short stiff form it assumes the characters of JRytiphloea thuyoides so strongly, 
that nothing but the microscope can separate them. (See under JRytiphloea thuyoides,) 
Fig. 122. POLYSIPHONIA AFFINIS. 
Colour. A dull, pale, reddish-brown. 
Substance. Firm below ; soft above. 
Character of Frond. Long tufts of jointed threads (^filaments) much branched. Stems as thick 
as bristles below ; irregularly forked ; or alternately branched. Branches spreading ; 
naked at base, finely divided and ovate in outline above ; lesser branchlets all naked 
at base ; furnished above with a few very upright, alternate, or secund branchlets, 
the lowermost longest. Joints of the stem obscure ; those of the branches obvious ; 
marked with numerous upright lines (internal tubes). 
Internal Tubes. About sixteen. 
Measurement. From 4 to 8 inches long. 
Fructification. Of two kinds. 1. Clustered spores in ovate or nearly globose, stalked capsules ; 
external. 2. Tetraspores large ; immersed in the lesser branchlets. 
Habitat. Clamlough, near Glenarm, Ireland. Cushendall, ditto. On rocks, &c. in the sea, 
and thrown up from deep water. 
Dr. Harvey considers this almost too closely allied to P. oiigrescens. Its branching is more 
loose, its internal tubes fewer, its colour paler, its branches more wavy, and its substance 
softer. Yet he could be “ well contented to regard it as a deep-water form of that species.” 
Nevertheless, figures of the typical forms of each are different. (See the figures.) 
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