468 THE BRITISH NATURE BOOK 



The Peacock's Tail (Padina pavonia) derives its name from its shape, and 

 is only 2 or 3 inches in height. Though really a species of the tropics, it is 

 to be found on our South Coasts, and is identified by its shape, and by the con- 

 centric lines and bands, which are magnificently iridescent in water. It is 

 to be found quite commonly at Weymouth. 



The Net-weed (Dictyota dichotoma) is a delicate-looking seaweed, having 

 each frond cut in two at the top ; the surface, if examined closely, will be found 

 to exhibit a network of square or oblong meshes. It is light olive in colour, 

 and is found growing in tufts on stones and other weeds in our rock pools. 



Some of the seaweeds in this group are mere tufts of brown shaggy threads 

 growing on other weeds. Among them is Ectocarpus siliculosus, its name 

 implying that it has external fruit, in little pod-like bodies on the branches ; 

 but these must be examined with your pocket lens. Ectocarpus granulosus 

 is a similar minute plant without the pods, but with square-shaped cells show- 

 ing plainly through the magnifier. 



The Red Seaweeds (Rhodospermee) include some of the most graceful and 

 attractive of all, although they are very small. There are, for example, 

 more than twenty species of Cattithamnion (Gr. "beautiful shrub"), some 

 attaining a length of 6 inches, but the majority very minute, looking almost 

 like red velvet. The different kinds of Ceramium are sure to be noticed by 

 any collector. The Common Red has forked threads with tips turned towards 

 one another. Ceramium diaphanum has soft silky tufts, and white stems 

 with red joints. 



Plocamium coccineum, Braided Hair, has flat, crimson, hair-like branches, 

 serrated on one side like a finely toothed comb, much branched, but without 

 ribs or veins. This is one of the commonest species. 



Ptilota plumosa has feather-like fronds varying from 3 to 10 inches, and 

 can be identified by them, while Griffithsia setacea has stiffer, more bristle-like 

 fronds, which, when placed in fresh water, burst, shooting out the red colouring 

 matter within. 



Nitophyllum punctatum is a delicate plant, 6 to 10 inches in length and 

 breadth, rather like the Red Dock Leaf a large lettuce-like frond, crisped 

 and wavy at the edges, which are cut into lobes, those at the top being 

 forked. It has no midrib, and is thus distinguished from Wormskoldia and 

 Delesseria. 



The Wormskoldia sanguinea, Red Dock Leaf or ASH-LEAVED SEAWEED, is 

 magnificently scarlet-coloured, with fronds 5 to 6 inches long, extraordinarily 

 like those of a Dock, and very transparent. It has a strong midrib and 

 branching nervures, and is much folded or waved. It is at its best in June 

 and July, becoming ragged later on. 



Delesseria hypoglossum is a small plant, with fronds about J inch in length, 

 found on almost every coast. 



Delesseria alata is found growing in thick tufts on the stems of other weeds 

 for example, Laminaria digitata ; it possesses a slight midrib, on the edges of 



