Plate II. 



Fig. 5. CYSTOSEIEA GEANULATA. 



Colour, When fresli, semi-transparent olive; wlien dry, black; except tlie 

 younger shoots. 



Substance. Tougli_, 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 in- 

 • curved 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 to- 

 gether; small; oblong. 



Fructification. Minute seeds {sjjores) in special receptacles at the ends of the 

 branches, thickening them. Receptacles long and strongly tubercled; 

 an occasional spine. 



Habitat. South of England. Ireland generally. Rocky tide-pools. 



Fig. 6. CYSTOSEIEA FIBEOSA. 



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 deli- 

 cate thorn-like branchlets. 



Measurement. 3 feet or more, long. 



Air-vessels. Inflations in the branches towards the middle or lower part; oval, 

 large, sometimes 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 deli- 

 cate thorn -like branchlets. 



Habitat. England, west and south. Ireland, freqaent. Rocks near low-water 



mark; tide-pools; deep water. 



Infested by a minute, tufted, parasitic alga, Elachista flaccida ; for which see 

 ' Plate XV. Fig. 62. The very large air-vessels distinguish this Cystoseira from 

 every other. 



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