Fig. 19. DESMARESTIA VTRIDIS. 
Colour. When growing, a fine chestnnt-olive ; on exposure to air, turning verdigris-green ; 
when dry, resuming its proper hue. 
Snhstance. Tender and soon decomposing when gathered. Clinging in a sticky lump when 
exposed to the air. Eecovering itself when dry. 
Character of Frond. Thread-like, long, excessively branched. Branching uniformly opposite, 
on each side the stem, like a feather (^pinnate). Branches repeatedly branched ; always 
in the same manner ; becoming finer in every series, till they resemble hairs. 
Measurement. From 1 to 3 feet long. 
Fructification. Not ascertained. 
Habitat. Our shores generally. Between tide-marks ; not uncommon. 
Easy of detection from its exactly opposite branching throughout the whole frond. 
Though thread-like {filiform) in growth, it flattens when dried and pressed. 
Fig. 20. ARTHROCLADIA VILLOSA. 
Colour. Pale olive-green. 
Suhsta7ice. When fresh, stiff ; soon becoming limp {flaccid) on exposure to the air, 
Chai^acter of Frond. Thread-like, long, very slender stems ; several frond one base ; branched. 
Branches distant, horizontal ; on each side the stem ; commonly opposite. Branch- 
lets the same. Frond encircled {ivhorled) at short intervals -with minute knobs 
{nodes) bearing very delicate, pale-green, jointed, threads (fllamerits). 
Measui^ement. From 6 inches to nearly 3 feet long. 
Fructification. Minute seeds {spoi^es) in tiny pod-like receptacles, borne upon the hair-like 
filaments which surround the stems. 
Habitat. South of England, Frith of Forth, Wicklow and Downshire coasts. Bather rare. 
The distance of the branches from each other in this species characterises it even to those 
who do not look close enough to observe the ivhorls round the stems. 
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