366 THE SEA SHORE 



widely distributed over the English coasts. Its broad, fleshy fronds 

 are divided into finger-like lobes, and are either sessile or supported 

 on a stalk that proceeds from a small discoid root. The frond is 

 very variable in form, being sometimes divided into very narrow 

 segments, and sometimes quite undivided. One variety has a 

 number of small stalked leaflets on its margin (see Plate VIII.) ; 

 and another is very narrow, with wedge-shaped irregular lobes. 

 R. palmetto is a smaller and less common species that grows on 

 rocks and large weeds in deep water. The tetraspores form 

 crimson patches on the tips of the lobes. 



Maugeria (Delesseria) sanguinea (Plate VIII.) is a large and 

 beautiful weed, of a blood-red colour, that grows in the lower rock 

 pools or beyond low-water mark, under the shade of high rocks or 

 hidden by the olive tangles. Its frond is thin and membranous, 

 with a well-defined midrib. The spores are contained in globular 

 stalked conceptacles, usually on one side of the midrib ; and the 

 tetraspores may be seen in pod-like leaflets attached to the bare 

 midrib during the whiter. 



Passing over some of the rarer membranaceous Rhodymeniacece, 

 we come to the beautiful Plocamium, distinguished by its linear 

 compressed crimson fronds, which are pin- 

 nate, with comb-like teeth, the branchlets 

 being alternately arranged on either side 

 in threes and fours. The spores are on 

 radiating threads, in globular conceptacles ; 

 and the tetraspores are in the outer divi- 

 Fio. 251. Plocamium sions of the frond. We have only one 

 species of this beautiful genus, and that is 



P. coccineum, which is of such a brilliant colour that it is always 

 a favourite with collectors. 



Our last example of the order is Oordylecladia (Gracilaria) 

 erecta, with threadlike, cartilaginous frond, irregularly branched 

 and cellular in structure. The fronds arise from a disc-like root ; 

 and bear spores in thickly- clustered spherical conceptacles, and 

 tetraspores in lanceolate pods at the tips of the branches, both 

 in the winter. It is a small weed, and grows principally on sand- 

 covered rocks near low-water mark. 



The order Sphcerococcoidece contains red or purple sea weeds 

 with unjointed cartilaginous or membranaceous fronds, composed 

 of many-sided, elongated cells, with spores in necklace-Like strings, 

 lodged in external conceptacles. The typical genus (Sphcerococcus) 



