MELANOSPERME2X. 33 
picturesque appearance ; the olive green of the channelled fronds of this 
species mingled with the golden tint of its clustered seed vessels, produces 
the most charming effect. The tufted fronds of this species are from 2in. 
to 6in. high, and are channelled on the upper side, but it has neither air- 
vessels nor midrib like some of its congeners. The fruit is contained in 
Fig. 35. Fucus nodosus. Fig. 36. Fucus serratus. 
oblong wedge-shaped receptacles, which are produced at the tips of the 
branches ; our illustration is from a fruited specimen. The root, as in 
most of the Fuci, is a slightly conical disk, which adheres very firmly to 
the rocks precisely in the same manner as a pneumatic bracket. Descending 
a short distance from high-water mark, the observer very soon meets with 
F, nodosus (Fig. 35), or the “knobbed wrack,’’ which is stunted, and 
sparingly provided with air vessels until it is found in situations where it 
can float on the surface of the water for a considerable part of the day. 
Such specimens when fully grown are above 3ft. or 4ft. long, and the 
air vessels which swell out at intervals along the stem and branches are 
often fully as large as a plover’s egg. These air vessels help to sustain the 
heavy fronds in a floating: position, and when the tide recedes, and the 
plant is spread out on the flat rocks on some shores, pedestrians are 
often startled at the popping sounds under their feet as they tread on the 
air bladders of this rockweed. The illustration shows the plant in a fruited 
and barren condition. The fruit is contained in roundish stalked vessels of 
a bright yellow colour, which spring from both sides of the branches. The 
fronds have no midrib, and are quite smooth and glossy. The rare species, 
F, Mackaii,is found on the west coast of Ireland and Scotland, though 
not to my knowledge on the English shores. It is intermediate between 
the two foregoing species, and is easily distinguished from both by the 
form and position of its fruit vessels, which are pendulous, and are 
produced near the base of the branches. F. serratus (Fig. 36), or the 
