Plate IL 
Fig. 5. CYSTOSEIEA GRANULATA. 
Colour. When fresh, semi-transparent olive ; when dry, black ; except the younger shoots. 
Substance. Tough, leathery ; the young shoots more delicate. 
Character of Frond. Shrub-like. Stem cylindrical; thick; short; covered with bulbous 
knobs, from each of which springs a branch. Branches slender, repeatedly divided 
and branched ; irregularly set with thorn-like, incurved branchlets, having a tendency 
to a knob-like origin. 
Measurement. Stem, 7 to 8 inches ; branches, 1 foot or more, long, 
Air--vessels. Inflations in the upper part of the branches ; two or three together ; small ; 
oblong. 
Fructification. Minute seeds {spores) in special receptacles at the ends of the branches, 
thickening them. Eeceptacles long and strongly tubercled ; an occasional spine. 
Habitat. South of England. Ireland generally. Rocky tide-pools. 
Fig. 6. CYSTOSEIEA FIBROSA. 
Colour. When fresh, yellowish olive ; when dry, perfectly black. 
Substance. Tough, leathery ; when dry, brittle. 
Character of Frond. Shrub-like. Stem, compressed ; woody ; very much branched. Branches 
very slender ; the upper ones clothed with delicate thorn-like branchlets, 
Measurement. 3 feet or more, long. 
Air-vessels. Inflations in the branches towards the middle or lower part ; oval, large, some- 
times thorny ; one, two, or three near each other ; often very abundant on the plant. 
Fructification. Minute seeds {spores) in special receptacles at the ends of the branches, 
thickening them. Receptacles very long ; clothed with delicate thorn-like branchlets. 
Habitat. England, west and south. Ireland, frequent. Rocks near low-water mark ; tide- 
pools ; deep water. 
Infested by a minute, tufted, parasitic alga, ElacMsta fiaccida; for which see Plate XV. 
Fig. 62. The very large air-vessels distinguish this Cystoseira from every other. 
