Plate XXV. 



Fig. 107. DASYA VENUSTA. 



Colour. Kosy red; steins brownish. Stihstance. Very soft; tender. 



Character of Frond. Thread-like {filamentous) ; much branched. Stem long, simple, 

 semi-transparent, unjointed. Branches alternate; the lowermost longest; the 

 rest gradually shorter upwards, giving the front a pyramidal outline; once or 

 twice re-branched like a feather (^innnate)\ unjointed; but clothed throughout 

 with very slender, hair-like branchlets, which are jointed and many times 

 forked (dicliotomous). 



Measurement. From 3 to 4 inches long. 



Fructification. Of two kinds; external. 1. Clustered spores in ovate capsules, with 

 a protruding mouth {urceolate, see figure) ; unstalked. 2. Tetraspores in pointed 

 oblong, stlchidla; stalked. 



Habitat. Jersey. Cast ashore. Very rare. 



Fig. 108. RITIPHLCEA COMPLANATA. 



Colour. Brown-red; becoming almost black in drying. Substance. Firm, elastic. 



Character of Frond. Thread-like {filamentous), but compressed; much branched. 

 Filaments opaque; closely marked with lines across (transversely striate). 

 Stem erect; nearly simple below; much branched above. Branches erect, but 

 spreading; twice or thrice re-branched, like a feather {pinnate); the lower 

 branchlets always short or stunted; the upper longer, straight, rod-like; giving 

 a stiff, formal character to the plant. 



Measurement. From 2 to 3 inches long. 



Fructification. Has not been found in Britain. 



Hahitat. South of England and West of Ireland (Miltown Malbay, in one particular 

 pool, abundant). On the rocky beds of shallow tide-pools, exposed at low- 

 water mark to full sunshine. Very rare. 



The lines across {transverse strice) characteristic of the s^cnus, look in this 

 species as if they were arched, but this is an optical delusion. They are best 

 observed through a pocket lens. 



Fig. 109. POLYSIPHONIA URCEOLATA. 



Colour. Full red; becoming dark in drying. Substance. Kigid; wiry. 



Character of Frond. Long, dense, bushy tufts of jointed threads (filaments); much 

 branched; loosely entangled. Branches partly forked {sub-dic]iotomous)\ partly 

 alternate; erect, but spreading; more or less furnished with very short, alternate, 

 spreading or back-curved (re-curved) branchlets. Joints marked with two broad 

 upright lines (internal tubes seen through); or, if the filament be twisted, part 

 of a third becoming visible. 



Internal Tubes. Four. 



Measurement. From 3 to 9 inches long. 



Fructification. Of two kinds. 1. Clustered spores in capsules; external. Capsules 

 generally stalked, ovate, with a protruding mouth (urceolate). 2. Tetraspores 

 immersed in the upper part of swollen branchlets. 



Hahitat. Our coasts generally. On rocks between tide-marks, or on the stems of 

 Laminaria digitata. Common. 



Varying very much in delicacy. Often as thick as horsehair at the base of 

 the filaments, but sometimes approaching the slenderness of P. formosa. It is 

 always more rigid in substance, however, and its short back-curved branchlets 

 are another mark of distinction, particularly in specimens growing on L. digitata. 



49 II 



