Plate IV. 
Fig. 13. FUCUS NODOSUS. 
Colour. When fresh, olive-green ; glossy ; yellower in youth ; when dry, black. 
Substance. Densely tough and leathery. 
Character of Frond. Compressed narrow straps, several springing from a root; thick; 
branched. Branching partly forked {dichotomous), partly on each side of a stem, like 
a feather {pinnate). Margins toothed {serrated) at remote intervals. 
Measurement. From 2 to 6 feet long. 
Air-vessels. Inflations in the branches, swelling them out far beyond the margins ; very large, 
oblong. 
Fructification. Minute seeds {spores) in special receptacles at the sides of the branches. 
Receptacles, globose ; on stalks ; growing from the axils of the marginal teeth ; 
slimy ; bright yellow. 
Habitat. All round the coast ; very common ; between high-water mark and half-tide level. 
Now Fucodium nodosum. 
Fig. 14. FUCUS MACKAII. 
Colour. When fresh, dull olive-green ; when dry, black. 
Substance. Tough, leathery ; when dry, rather horny. 
Character of Frond. Cylindrical except at the base ; slender ; branched. Branching forked 
{dichotomous). Branches crowded, spreading. 
Measurement. From 6 to 10 inches long. 
Air-vessels. Inflations in the branches ; here and there one, alone ; longish oval ; wider than 
the branch. 
Fructification. Minute seeds {spores) in special receptacles at the sides of the branches towards 
-fhe base. Receptacles on long drooping stalks ; more or less ovate ; sometimes one, 
sometimes two from a stalk ; the two forming a fork. 
Habitat. West of Ireland. On muddy sea-shores. Not rooted, but resting on mud or in 
gravel among large stones. 
Now Fucodmm Mackaii. 
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