Plate XXVI. 

 Fig. 113. POLYSIPHONIA FIBRATA. 



Colour. Dark red-brown below; rosy above. 



Substance. Tender and gelatinous; decomposing rapidly in fresh-water. 



Character of Frond. Very dense tufts of jointed threads {filaments)] much branched. 

 Stems as thick as hog's bristles below, becoming very fine upwards; simple or 

 alternately branched. Set at greater or less distances with very slender, forked 

 {dicliotomous) branchlets, more or less tufted; whose abrupt {truncate) tips 

 are clothed with colourless, forked {dichotomous) fibres, bearing at certain 

 seasons tiny yellow pods {antheridia), whose office is not thoroughly ascertained. 

 Angles of branching {axils) all spreading. Marked throughout with two 

 upright lines (internal tubes). 



Internal Tubes. Four. 



Measurement. From 2 to 10 inches long. 



Fructification. Of two kinds. 1. Clustered spores in ovate or globose capsules; 

 external; plentifully scattered. 2. Tetraspores immersed in the swollen upper 

 branchlets. 



Habitat. Our coasts generally. On rocks, stones, and algae, between tide-marks. 

 Not uncommon. 



Fig. 114. POLYSIPHONIA SPINULOSA. 



Colour. Dark red. Substance. Eigid, though fine. 



Character of Frond. Short, delicate tufts of jointed threads {filaments) very much 

 branched. Branching alternate. Branches spreading; irregularly set; clothed 

 with short, straight, spreading branchlets; several times re-branched; the last 

 set, thorn-like, and horizontally spread; their tips sometimes minutely divided; 

 each division bearing a long, colourless, jointed thread. Joints marked by 

 two or three upright lines (internal tubes). 



Internal Tubes. Four large and several lesser ones; more of these in the branches 

 than branchlets. 



3Ieasurement. One or 2 inches long. 



Fructification. Only one sort observed. Clustered spores in globose, unstalked 



{sessile) capsules; external. 

 Habitat. Appin. Very rare. 



A plant which, like the next, has only been found once; the solitary specimens 

 being preserved in Sir William Hooker's Herbarium. 



Fig. 115. POLYSIPHONIA RICHARDSONI. 



Colour. Dull red; becoming darker in drying. Substance. Rigid; elastic. 



Character of Frond. Small tufts of jointed threads {filaments) much branched. 

 Stem, hogs'-bristle thickness at base; finer above; alternately branched through- 

 out; the branches long, spreading, often issuing horizontally; set in the upper 

 part with widely-spreading, straight, partly forked {sub-dichotomous), partly 

 alternate branchlets. Main joints marked with several irregular lines (internal 

 tubes), twisted. 



Internal Tubes. Five. 



Measurement. Three or 4 inches long. 



Fructification. Only one kind observed. Clustered spores in globose, unstalked 



{sessile) capsules; external. 

 Habitat. Colvend, Dumfries. 

 61 



