Plate X. 



Fig. 37. DICTYOTA DICIIOTOMA. 



Colour. Olive; more or less green or brown. 

 SuhstaMce. Thin; semi-transparent; membranaceous. 



Character of Frond. Flat; ribless; narrowish througliout ; brancliecl. Branch- 

 ing, forked [dicJiotomous) throughout; the frond becoming narrower 

 upwards. Margins entire. Root woolly. 



Measurement. From 3 to 12 inches long. Width varying from ^ of an 

 inch to an almost hair-like fineness. The average width is represented 

 in the figure. 



Fructification. Minute seeds [spores] on both surfaces of the frond; either 

 in oval clusters or irregularly scattered. 



Habitat. Our shores generally. On rocks and sea-plants between tide-marks. 

 Common. 



The narrow variety {J), irdrlcata) is troublesome to lay out; being truly "much 

 branched, twisted, and entangled." 



Fig. 38. STILOPHORA RHIZODES. 



Colour. A greenish olive when young; when old_, foxy brown. 



Substance. Elastic and gristly when fresh, but soon turning soft and gela- 

 tinous in fresh water. 



Character of Frond. Thread-shaped [filiform) ; solitary or tufted; branched. 

 Branching irregular; mostly forked [dichotomous) ; occasionally alternate. 

 Root, a disc. 



Measurement. From 6 inches to 2 feet long. 



Fructification. Minute seeds [spores) in convex, wartlike clusters, densely 

 covering the surface of the frond, and giving it a dotted appearance. 



Habitat. Shores of England and Ireland, Jersey. Near low-water mark, 

 growing on rocks or algse. 

 19 



