SEA WEEDS 355 



narrower fronds, of a more regular shape and of a bright-green 

 colour. The fronds are composed of two layers of cells. 



The Ulvce retain their colour perfectly when dried, and, with the 

 exception of U. latissima, are of a mucilaginous nature, and adhere 

 well to paper, but, unfortunately, the graceful wavy outline of the 

 fronds is lost in pressed specimens. 



The ' true laver ' mentioned above, which is also popularly 

 known as Sloke, is closely allied to Ulva, but may be distinguished 

 from it by the colour of its membranous fronds, which vary from 

 a light rose to a deep purple or violet, occasionally inclining to 

 olive, but never green. Its scientific name is Porphyra laciniata 

 (Plate VII.), and it differs from the majority of the chlorospermece in 

 having dark-purple spores, which are arranged in groups of four in 

 all parts of the frond. The fronds are very variable in form and 

 size, being sometimes ribbon-like, and sometimes spreading into an 

 irregular sheet of deeply-divided segments ; and the remarkable 

 variety of form and colour has led to a division into several species. 

 These, however, merge into one another so gradually that the sepa- 

 ration seems to be hardly necessary. 



The same remark concerning the multiplicity of species applies 

 to another allied genus called Enteromorpha, in which the fronds 

 are green and tubular, and often more or less branched. In these 

 the colour varies from a pale to a dark green, and the cells are 

 arranged in such a manner as to give a reticulated appearance. The 

 commonest and best-defined species are E. intestinalis, the tubular 

 fronds of which are constricted at intervals in such a manner as 

 to resemble the intestines of an animal, and E. compressa, with 

 branched fronds of variable form and size. The former is common 

 on all our coasts, and may even be found in rivers and ditches 

 some distance from the sea. It thrives equally well in fresh and 

 salt water, and appears to grow most luxuriantly in the brackish 

 waters of tidal rivers. The latter species also thrives best in similar 

 situations. 



Coming now to the red-spored sea weeds (Rhodospermece), we 

 have to deal with some of the most charming of the marine algae 

 that invariably attract the sea- side rambler, and provide many of 

 the most delightful objects in the album of the young collector. 

 Their brilliant colours, varying from a light red to dark purple and 

 violet, are sufficient in themselves to render them popular with the 

 collector, but in addition to this striking feature they are characterised 

 by extreme elegance of form and delicacy of texture. They are to 



