872 THE SEA SHOBE 



containing crimson pear-shaped spores. Another species (L. ovalis), 

 found on the coasts of Devon and Cornwall, may be recognised by 

 its solid branched frond and little oval leaf-like branchlets, which 

 are hollow, jointed, and divided by partitions internally. 



The one remaining order of the red-spored sea weeds is the 

 Bhodomelacece, which has either a jointed or a many-tubed axis, 

 and the surface divided up into little definite areas. The fronds are 

 either leafy or thread-like, and the prevailing colours are red, reddish 

 brown, and purple. The spores are pear-shaped, and occupy the 

 terminal cells of tufted threads in external, globular, or rounded con- 

 ceptacles ; and the tetraspores are lodged in special receptacles, or 

 in special modified branchlets. The order contains some of our 

 most beautiful weeds, while some of its members are of a very dark 

 colour and unattractive form. 



The typical genus Rhodomela contains two British species 

 with dark-red, cartilaginous fronds, cylindrical, unjointed, and 

 irregularly branched ; and the tetraspores imbedded in the tips of 

 the slender branchlets. The name of the genus signifies ' red-black,' 

 and is applied on account of the tendency of the dark -red fronds to 

 turn black when dried. 



JR. subfusca is very common on all our coasts. It has rigid 

 fronds, irregularly branched ; and is in its best condition during the 

 summer. The other species B. lycopodioides has long undivided 

 branches with thickly-set and freely- divided branchlets. 



When turning over the fronds of different species of the larger 

 olive weeds we commonly find them more or less clothed with tufts 

 of filamentous plants, sometimes small and delicate, and sometimes 

 larger and of more robust growth, varying in colour from a purplish 

 brown to a dark violet, and the articulated filaments more or less 

 distinctly striated with parallel lines. These weeds belong to 

 the genus Polysiphonia, and derive their generic name from the 

 fact that the threadlike fronds are composed of several parallel 

 tubes. The surface cells are also arranged in regular transverse 

 rows, and it is this which gives rise to the striated appearance above 

 referred to. 



Over twenty species of Polysiphonia are to be found on our shores, 

 where they exist at all levels between the tide-marks. They are 

 distinguished from one another partly by their general form and 

 mode of growth, and also by the number of tubes in their threadlike 

 fronds. 



Although they would not always be considered as lovely weeds 



