pucacejE. 43 



This is not a common plant. It resembles F. vesicu- 

 losus, but may be readily distinguished by its narrow 

 side-branches, its thinner texture, and the smaller quan- 

 tity of saline matter which it contains. This latter pe- 

 culiarity causes it to require less soaking, and to dry 

 more quickly than other species of the genus. 



Fucus serratus. Serrated Wrack. 



Frond flat, forked, toothed at the edge, having a strong 

 midrib, from two to four feet long, or more. Air-vessels, 

 none. Spore-receptacles flat, at the ends of the branches. 



This species is very common, and is easily identified. 

 The width of the frond and the depth of its serratures 

 vary considerably j but the general character of the 

 plant is never lost. 



Fucus nodosus. Knotted Wrack, or Sea- 

 whistles. 



Frond flattened, without a distinct midrib, one to five 

 feet long, a quarter of an inch to an incli wide ; branches 

 springing from slight projections, small at the base, and 

 more or less pointed at the apex. Air-vessels very large, 

 oval, formed in the main stem and branches. Spore-recep- 

 tacles egg-shaped, on erect slender stalks, springing from 

 projections on the branches, bright yellow when ripe. 



This is the largest, toughest, and most rigid British Fu- 

 cus. It grows nearer to low-water mark than any other 

 species of the genus, and is usually more or less covered 

 with Polysiphonia fastigiata. It may be easily recog- 

 nized by its thick narrow frond and large air-vessels. 



