Plate III. 
Fig. 9. PYCNOPHYCUS TUBERCULATUS. 
Colour. When growing, a fine olive ; when dry, black. 
Substance. Tough, leathery. Brittle when dry. 
Character of Frond. Cylindrical ; about as thick as a goosequill ; branched. Branching, 
repeatedly forked {dichotomous). Root fibrous. 
Measurement. From 12 to 20 inches long. 
Air-vessels. Inflations in the branches ; but often wanting. 
Fructification. Minute seeds (spores) in special receptacles at the ends of the branches, 
thickening them. Receptacles long ; obtuse at the tips ; tubercled ; yellowish. 
Habitat. Cornwall and Devonshire. West of Ireland. Jersey. In rock-pools near low- 
water mark. 
By a change of classification and name, this plant is now Fucodium tuberculatum. The 
Family Fucodium comprehending also- those members of the old Family Fucus, which are 
destitute of a midrib ; viz. F. nodosus, F. Mackaii, and F. canaliculatus. 
Fig. 10. FUCUS VESICULOSUS. 
Colour. When fresh, olive-brown ; when dry, black. 
Substance. Tough, leathery ; slimy feeling. 
Character of Frond. Flat, midribbed, branched, occasionally twisted ; branching, forked 
(dichotomous) ; margins smooth (entire). 
Measurement. Sometimes extending to several feet in length. Dwarf varieties from 1 to 2 inches. 
Air-vessels. Inflations in the branches ; round 5 largish ; mostly in pairs ; often one on each 
side the midrib. But air-vessels are not unfrequently wanting. 
Fructification. Minute seeds (spores) in special receptacles at the ends of the branches. 
Receptacles more or less oval ; large ; orange-coloured ; slimy ; tubercled. 
Habitat. All round our coasts ; abundant. On all rocks, stones, piers, quays, &c. which become 
exposed at low water. Up rivers too, in similar situations, as long as the water 
is brackish ; but under such circumstances dwarfed and destitute of air-vessels. 
A most widely distributed species. Found on the North Atlantic coasts, and extends even 
to the Troincs, Arctic Ocean, and Pacific coasts of N. America, Kamschatka, &c. 
5 
